diff --git a/src/com/google/javascript/jscomp/LinkedFlowScope.java b/src/com/google/javascript/jscomp/LinkedFlowScope.java
index 6e279bd9c4a..6dfbaee8dc8 100644
--- a/src/com/google/javascript/jscomp/LinkedFlowScope.java
+++ b/src/com/google/javascript/jscomp/LinkedFlowScope.java
@@ -204,26 +204,13 @@ public StaticTypedSlot getOwnSlot(String name) {
   }
 
   @Override
-  public FlowScope createChildFlowScope() {
-    return this;
-  }
-
-  @Override
-  public FlowScope createChildFlowScope(StaticTypedScope scope) {
+  public FlowScope withSyntacticScope(StaticTypedScope scope) {
     TypedScope typedScope = (TypedScope) scope;
     return scope != syntacticScope
         ? new LinkedFlowScope(trimScopes(typedScope), typedScope, functionScope)
         : this;
   }
 
-  /**
-   * Remove flow scopes that add nothing to the flow.
-   */
-  @Override
-  public LinkedFlowScope optimize() {
-    return this;
-  }
-
   @Override
   public TypedScope getDeclarationScope() {
     return syntacticScope;
@@ -247,7 +234,7 @@ public FlowScope apply(FlowScope a, FlowScope b) {
       // To join the two scopes, we have to
       LinkedFlowScope linkedA = (LinkedFlowScope) a;
       LinkedFlowScope linkedB = (LinkedFlowScope) b;
-      if (linkedA == linkedB) {
+      if (linkedA.scopes == linkedB.scopes && linkedA.functionScope == linkedB.functionScope) {
         return linkedA;
       }
 
@@ -288,11 +275,7 @@ public boolean equals(Object other) {
     if (!(other instanceof LinkedFlowScope)) {
       return false;
     }
-
     LinkedFlowScope that = (LinkedFlowScope) other;
-    if (this == that) {
-      return true;
-    }
 
     // If two flow scopes are in the same function, then they could have
     // two possible function scopes: the real one and the BOTTOM scope.
@@ -302,11 +285,8 @@ public boolean equals(Object other) {
     // they're equal--this just means that data flow analysis will have
     // to propagate the entry lattice a little bit further than it
     // really needs to. Everything will still come out ok.
-    if (this.functionScope != that.functionScope) {
-      return false;
-    }
-
-    return this.scopes.equivalent(that.scopes, LinkedFlowScope::equalScopes);
+    return this.functionScope == that.functionScope
+        && this.scopes.equivalent(that.scopes, LinkedFlowScope::equalScopes);
   }
 
   private static boolean equalScopes(OverlayScope left, OverlayScope right) {
@@ -320,7 +300,7 @@ private static boolean equalScopes(OverlayScope left, OverlayScope right) {
    * Determines whether two slots are meaningfully different for the purposes of data flow analysis.
    */
   private static boolean equalSlots(StaticTypedSlot slotA, StaticTypedSlot slotB) {
-    return !slotA.getType().differsFrom(slotB.getType());
+    return slotA == slotB || !slotA.getType().differsFrom(slotB.getType());
   }
 
   @Override
diff --git a/src/com/google/javascript/jscomp/TypeInference.java b/src/com/google/javascript/jscomp/TypeInference.java
index 6a78d83ba6a..c508eb73a4e 100644
--- a/src/com/google/javascript/jscomp/TypeInference.java
+++ b/src/com/google/javascript/jscomp/TypeInference.java
@@ -215,7 +215,7 @@ FlowScope flowThrough(Node n, FlowScope input) {
     }
 
     Node root = NodeUtil.getEnclosingScopeRoot(n);
-    FlowScope output = input.createChildFlowScope(scopeCreator.createScope(root));
+    FlowScope output = input.withSyntacticScope(scopeCreator.createScope(root));
     output = inferDeclarativelyUnboundVarsWithoutTypes(output);
     output = traverse(n, output);
     return output;
@@ -246,7 +246,7 @@ List<FlowScope> branchedFlowThrough(Node source, FlowScope input) {
             Node item = source.getFirstChild();
             Node obj = item.getNext();
 
-            FlowScope informed = traverse(obj, output.createChildFlowScope());
+            FlowScope informed = traverse(obj, output);
 
             if (NodeUtil.isNameDeclaration(item)) {
               item = item.getFirstChild();
@@ -294,8 +294,7 @@ List<FlowScope> branchedFlowThrough(Node source, FlowScope input) {
               // conditionFlowScope is cached from previous iterations
               // of the loop.
               if (conditionFlowScope == null) {
-                conditionFlowScope = traverse(
-                    condition.getFirstChild(), output.createChildFlowScope());
+                conditionFlowScope = traverse(condition.getFirstChild(), output);
               }
             }
           }
@@ -319,8 +318,8 @@ List<FlowScope> branchedFlowThrough(Node source, FlowScope input) {
               if (conditionOutcomes == null) {
                 conditionOutcomes =
                     condition.isAnd()
-                        ? traverseAnd(condition, output.createChildFlowScope())
-                        : traverseOr(condition, output.createChildFlowScope());
+                        ? traverseAnd(condition, output)
+                        : traverseOr(condition, output);
               }
               newScope =
                   reverseInterpreter.getPreciserScopeKnowingConditionOutcome(
@@ -332,8 +331,7 @@ List<FlowScope> branchedFlowThrough(Node source, FlowScope input) {
               // conditionFlowScope is cached from previous iterations
               // of the loop.
               if (conditionFlowScope == null) {
-                conditionFlowScope =
-                    traverse(condition, output.createChildFlowScope());
+                conditionFlowScope = traverse(condition, output);
               }
               newScope =
                   reverseInterpreter.getPreciserScopeKnowingConditionOutcome(
@@ -345,7 +343,7 @@ List<FlowScope> branchedFlowThrough(Node source, FlowScope input) {
           break;
       }
 
-      result.add(newScope.optimize());
+      result.add(newScope);
     }
     return result;
   }
@@ -365,13 +363,11 @@ private FlowScope traverse(Node n, FlowScope scope) {
         break;
 
       case AND:
-        scope = traverseAnd(n, scope).getJoinedFlowScope()
-            .createChildFlowScope();
+        scope = traverseAnd(n, scope).getJoinedFlowScope();
         break;
 
       case OR:
-        scope = traverseOr(n, scope).getJoinedFlowScope()
-            .createChildFlowScope();
+        scope = traverseOr(n, scope).getJoinedFlowScope();
         break;
 
       case HOOK:
@@ -1070,10 +1066,10 @@ private FlowScope traverseHook(Node n, FlowScope scope) {
             condition, scope, false);
 
     // traverse the true node with the trueScope
-    traverse(trueNode, trueScope.createChildFlowScope());
+    traverse(trueNode, trueScope);
 
     // traverse the false node with the falseScope
-    traverse(falseNode, falseScope.createChildFlowScope());
+    traverse(falseNode, falseScope);
 
     // meet true and false nodes' types and assign
     JSType trueType = trueNode.getJSType();
@@ -1084,7 +1080,7 @@ private FlowScope traverseHook(Node n, FlowScope scope) {
       n.setJSType(null);
     }
 
-    return scope.createChildFlowScope();
+    return scope;
   }
 
   /** @param n A non-constructor function invocation, i.e. CALL or TAGGED_TEMPLATELIT */
@@ -1153,7 +1149,6 @@ private FlowScope narrowScope(FlowScope scope, Node node, JSType narrowed) {
       return scope;
     }
 
-    scope = scope.createChildFlowScope();
     if (node.isGetProp()) {
       return scope.inferQualifiedSlot(
           node, node.getQualifiedName(), getJSType(node), narrowed, false);
@@ -1800,8 +1795,7 @@ private BooleanOutcomePair traverseShortCircuitingBinOp(
     Node right = n.getLastChild();
 
     // type the left node
-    BooleanOutcomePair leftOutcome = traverseWithinShortCircuitingBinOp(
-        left, scope.createChildFlowScope());
+    BooleanOutcomePair leftOutcome = traverseWithinShortCircuitingBinOp(left, scope);
     JSType leftType = left.getJSType();
 
     // reverse abstract interpret the left node to produce the correct
@@ -1811,8 +1805,7 @@ private BooleanOutcomePair traverseShortCircuitingBinOp(
             left, leftOutcome.getOutcomeFlowScope(left.getToken(), nIsAnd), nIsAnd);
 
     // type the right node
-    BooleanOutcomePair rightOutcome = traverseWithinShortCircuitingBinOp(
-        right, rightScope.createChildFlowScope());
+    BooleanOutcomePair rightOutcome = traverseWithinShortCircuitingBinOp(right, rightScope);
     JSType rightType = right.getJSType();
 
     JSType type;
diff --git a/src/com/google/javascript/jscomp/type/ClosureReverseAbstractInterpreter.java b/src/com/google/javascript/jscomp/type/ClosureReverseAbstractInterpreter.java
index f9783d85188..d40fa462abe 100644
--- a/src/com/google/javascript/jscomp/type/ClosureReverseAbstractInterpreter.java
+++ b/src/com/google/javascript/jscomp/type/ClosureReverseAbstractInterpreter.java
@@ -194,8 +194,7 @@ private FlowScope restrictParameter(
 
     // changing the scope
     if (type != null) {
-      FlowScope informed = blindScope.createChildFlowScope();
-      return declareNameInScope(informed, parameter, type);
+      return declareNameInScope(blindScope, parameter, type);
     } else {
       return blindScope;
     }
diff --git a/src/com/google/javascript/jscomp/type/FlowScope.java b/src/com/google/javascript/jscomp/type/FlowScope.java
index cdffd9c92f3..9a524da6546 100644
--- a/src/com/google/javascript/jscomp/type/FlowScope.java
+++ b/src/com/google/javascript/jscomp/type/FlowScope.java
@@ -33,16 +33,10 @@
 public interface FlowScope extends StaticTypedScope, LatticeElement {
 
   /**
-   * Creates a child of this flow scope, to represent an instruction
-   * directly following this one.
+   * Returns a flow scope with the given syntactic scope, which may be required to be a specific
+   * subclass, such as TypedScope.
    */
-  FlowScope createChildFlowScope();
-
-  /**
-   * Creates a child flow scope with the given syntactic scope, which may be required to be a
-   * specific subclass, such as TypedScope.
-   */
-  FlowScope createChildFlowScope(StaticTypedScope scope);
+  FlowScope withSyntacticScope(StaticTypedScope scope);
 
   /**
    * Returns a flow scope with the type of the given {@code symbol} updated to {@code type}.
@@ -67,11 +61,6 @@ public interface FlowScope extends StaticTypedScope, LatticeElement {
   FlowScope inferQualifiedSlot(
       Node node, String symbol, JSType bottomType, JSType inferredType, boolean declare);
 
-  /**
-   * Optimize this scope and return a new FlowScope with faster lookup.
-   */
-  FlowScope optimize();
-
   /** Returns the underlying TypedScope. */
   StaticTypedScope getDeclarationScope();
 }
diff --git a/src/com/google/javascript/jscomp/type/SemanticReverseAbstractInterpreter.java b/src/com/google/javascript/jscomp/type/SemanticReverseAbstractInterpreter.java
index cbb3f545408..ddc664f99fd 100644
--- a/src/com/google/javascript/jscomp/type/SemanticReverseAbstractInterpreter.java
+++ b/src/com/google/javascript/jscomp/type/SemanticReverseAbstractInterpreter.java
@@ -368,7 +368,7 @@ private FlowScope caseAndOrMaybeShortCircuiting(
       // If we did create a more precise scope, blindScope has a child and
       // it is frozen. We can't just throw it away to return it. So we
       // must create a child instead.
-      return unwrap(blindScope == leftScope ? blindScope : blindScope.createChildFlowScope());
+      return unwrap(blindScope);
     }
     refinements.clear();
     // Note: re-wrap the scope, in case it was unwrapped by a nested call to this method.
@@ -379,11 +379,10 @@ private FlowScope caseAndOrMaybeShortCircuiting(
     StaticTypedSlot rightVar =
         refinements.size() == 1 ? rightScope.getSlot(refinements.iterator().next()) : null;
     if (rightVar == null || !leftVar.getName().equals(rightVar.getName())) {
-      return unwrap(blindScope == rightScope ? blindScope : blindScope.createChildFlowScope());
+      return unwrap(blindScope);
     }
     JSType type = leftVar.getType().getLeastSupertype(rightVar.getType());
-    FlowScope informed = unwrap(blindScope).createChildFlowScope();
-    return informed.inferSlotType(leftVar.getName(), type);
+    return unwrap(blindScope).inferSlotType(leftVar.getName(), type);
   }
 
   /**
@@ -403,8 +402,7 @@ private FlowScope caseAndOrMaybeShortCircuiting(
   private FlowScope maybeRestrictName(
       FlowScope blindScope, Node node, JSType originalType, JSType restrictedType) {
     if (restrictedType != null && restrictedType != originalType) {
-      FlowScope informed = blindScope.createChildFlowScope();
-      return declareNameInScope(informed, node, restrictedType);
+      return declareNameInScope(blindScope, node, restrictedType);
     }
     return blindScope;
   }
@@ -424,7 +422,7 @@ private FlowScope maybeRestrictTwoNames(
     boolean shouldRefineRight =
         restrictedRightType != null && restrictedRightType != originalRightType;
     if (shouldRefineLeft || shouldRefineRight) {
-      FlowScope informed = blindScope.createChildFlowScope();
+      FlowScope informed = blindScope;
       if (shouldRefineLeft) {
         informed = declareNameInScope(informed, left, restrictedLeftType);
       }
@@ -501,9 +499,8 @@ private FlowScope caseIn(Node object, String propertyName, FlowScope blindScope)
       if (qualifiedName != null) {
         String propertyQualifiedName = qualifiedName + "." + propertyName;
         if (blindScope.getSlot(propertyQualifiedName) == null) {
-          FlowScope informed = blindScope.createChildFlowScope();
           JSType unknownType = typeRegistry.getNativeType(JSTypeNative.UNKNOWN_TYPE);
-          return informed.inferQualifiedSlot(
+          return blindScope.inferQualifiedSlot(
               object, propertyQualifiedName, unknownType, unknownType, false);
         }
       }
@@ -630,13 +627,8 @@ private static class RefinementTrackingFlowScope implements FlowScope {
     }
 
     @Override
-    public FlowScope createChildFlowScope() {
-      return new RefinementTrackingFlowScope(delegate.createChildFlowScope(), refinements);
-    }
-
-    @Override
-    public FlowScope createChildFlowScope(StaticTypedScope scope) {
-      return new RefinementTrackingFlowScope(delegate.createChildFlowScope(scope), refinements);
+    public FlowScope withSyntacticScope(StaticTypedScope scope) {
+      throw new UnsupportedOperationException();
     }
 
     @Override
@@ -656,11 +648,6 @@ private FlowScope wrap(FlowScope scope) {
       return scope != delegate ? new RefinementTrackingFlowScope(scope, refinements) : this;
     }
 
-    @Override
-    public FlowScope optimize() {
-      return wrap(delegate.optimize());
-    }
-
     @Override
     public StaticTypedScope getDeclarationScope() {
       return delegate.getDeclarationScope();
diff --git a/test/com/google/javascript/jscomp/LinkedFlowScopeTest.java b/test/com/google/javascript/jscomp/LinkedFlowScopeTest.java
index c45ee5a1220..08306451fbd 100644
--- a/test/com/google/javascript/jscomp/LinkedFlowScopeTest.java
+++ b/test/com/google/javascript/jscomp/LinkedFlowScopeTest.java
@@ -55,25 +55,10 @@ public void setUp() throws Exception {
     localEntry = LinkedFlowScope.createEntryLattice(localScope);
   }
 
-  public void testOptimize() {
-    assertEquals(localEntry, localEntry.optimize());
-
-    FlowScope child = localEntry.createChildFlowScope();
-    assertEquals(localEntry, child.optimize());
-
-    child = child.inferSlotType("localB", getNativeNumberType());
-    assertEquals(child, child.optimize());
-  }
-
   public void testJoin1() {
-    FlowScope childA = localEntry.createChildFlowScope();
-    childA = childA.inferSlotType("localB", getNativeNumberType());
-
-    FlowScope childAB = childA.createChildFlowScope();
-    childAB = childAB.inferSlotType("localB", getNativeStringType());
-
-    FlowScope childB = localEntry.createChildFlowScope();
-    childB = childB.inferSlotType("localB", getNativeBooleanType());
+    FlowScope childA = localEntry.inferSlotType("localB", getNativeNumberType());
+    FlowScope childAB = childA.inferSlotType("localB", getNativeStringType());
+    FlowScope childB = localEntry.inferSlotType("localB", getNativeBooleanType());
 
     assertTypeEquals(getNativeStringType(), childAB.getSlot("localB").getType());
     assertTypeEquals(getNativeBooleanType(), childB.getSlot("localB").getType());
@@ -96,11 +81,8 @@ public void testJoin1() {
   }
 
   public void testJoin2() {
-    FlowScope childA = localEntry.createChildFlowScope();
-    childA = childA.inferSlotType("localA", getNativeStringType());
-
-    FlowScope childB = localEntry.createChildFlowScope();
-    childB = childB.inferSlotType("globalB", getNativeBooleanType());
+    FlowScope childA = localEntry.inferSlotType("localA", getNativeStringType());
+    FlowScope childB = localEntry.inferSlotType("globalB", getNativeBooleanType());
 
     assertTypeEquals(getNativeStringType(), childA.getSlot("localA").getType());
     assertTypeEquals(getNativeBooleanType(), childB.getSlot("globalB").getType());
@@ -122,11 +104,8 @@ public void testJoin3() {
     localScope.declare("localC", null, getNativeStringType(), null);
     localScope.declare("localD", null, getNativeStringType(), null);
 
-    FlowScope childA = localEntry.createChildFlowScope();
-    childA = childA.inferSlotType("localC", getNativeNumberType());
-
-    FlowScope childB = localEntry.createChildFlowScope();
-    childA = childA.inferSlotType("localD", getNativeBooleanType());
+    FlowScope childA = localEntry.inferSlotType("localC", getNativeNumberType());
+    FlowScope childB = localEntry.inferSlotType("localD", getNativeBooleanType());
 
     FlowScope joined = join(childB, childA);
     assertTypeEquals(
@@ -148,13 +127,10 @@ public void testJoin3() {
         join(childB, childA), join(childA, childB));
   }
 
-  /**
-   * Create a long chain of flow scopes where each link in the chain
-   * contains one slot.
-   */
-  public void testLongChain1() {
-    FlowScope chainA = localEntry.createChildFlowScope();
-    FlowScope chainB = localEntry.createChildFlowScope();
+  /** Create a long chain of flow scopes. */
+  public void testLongChain() {
+    FlowScope chainA = localEntry;
+    FlowScope chainB = localEntry;
     for (int i = 0; i < LONG_CHAIN_LENGTH; i++) {
       localScope.declare("local" + i, null, null, null);
       chainA =
@@ -163,67 +139,8 @@ public void testLongChain1() {
       chainB =
           chainB.inferSlotType(
               "local" + i, i % 3 == 0 ? getNativeStringType() : getNativeBooleanType());
-
-      chainA = chainA.createChildFlowScope();
-      chainB = chainB.createChildFlowScope();
     }
 
-    verifyLongChains(chainA, chainB);
-  }
-
-  /**
-   * Create a long chain of flow scopes where each link in the chain
-   * contains 7 slots.
-   */
-  public void testLongChain2() {
-    FlowScope chainA = localEntry.createChildFlowScope();
-    FlowScope chainB = localEntry.createChildFlowScope();
-    for (int i = 0; i < LONG_CHAIN_LENGTH * 7; i++) {
-      localScope.declare("local" + i, null, null, null);
-      chainA =
-          chainA.inferSlotType(
-              "local" + i, i % 2 == 0 ? getNativeNumberType() : getNativeBooleanType());
-      chainB =
-          chainB.inferSlotType(
-              "local" + i, i % 3 == 0 ? getNativeStringType() : getNativeBooleanType());
-
-      if (i % 7 == 0) {
-        chainA = chainA.createChildFlowScope();
-        chainB = chainB.createChildFlowScope();
-      }
-    }
-
-    verifyLongChains(chainA, chainB);
-  }
-
-  /**
-   * Create a long chain of flow scopes where every 4 links in the chain
-   * contain a slot.
-   */
-  public void testLongChain3() {
-    FlowScope chainA = localEntry.createChildFlowScope();
-    FlowScope chainB = localEntry.createChildFlowScope();
-    for (int i = 0; i < LONG_CHAIN_LENGTH * 7; i++) {
-      if (i % 7 == 0) {
-        int j = i / 7;
-        localScope.declare("local" + j, null, null, null);
-        chainA =
-            chainA.inferSlotType(
-                "local" + j, j % 2 == 0 ? getNativeNumberType() : getNativeBooleanType());
-        chainB =
-            chainB.inferSlotType(
-                "local" + j, j % 3 == 0 ? getNativeStringType() : getNativeBooleanType());
-      }
-
-      chainA = chainA.createChildFlowScope();
-      chainB = chainB.createChildFlowScope();
-    }
-
-    verifyLongChains(chainA, chainB);
-  }
-
-  // Common chain verification for testLongChainN for all N.
-  private void verifyLongChains(FlowScope chainA, FlowScope chainB) {
     FlowScope joined = join(chainA, chainB);
     for (int i = 0; i < LONG_CHAIN_LENGTH; i++) {
       assertTypeEquals(
@@ -254,20 +171,11 @@ private void verifyLongChains(FlowScope chainA, FlowScope chainB) {
   }
 
   public void testDiffer1() {
-    FlowScope childA = localEntry.createChildFlowScope();
-    childA = childA.inferSlotType("localB", getNativeNumberType());
-
-    FlowScope childAB = childA.createChildFlowScope();
-    childAB = childAB.inferSlotType("localB", getNativeStringType());
-
-    FlowScope childABC = childAB.createChildFlowScope();
-    childABC = childABC.inferSlotType("localA", getNativeBooleanType());
-
-    FlowScope childB = childAB.createChildFlowScope();
-    childB = childB.inferSlotType("localB", getNativeStringType());
-
-    FlowScope childBC = childB.createChildFlowScope();
-    childBC = childBC.inferSlotType("localA", getNativeNoType());
+    FlowScope childA = localEntry.inferSlotType("localB", getNativeNumberType());
+    FlowScope childAB = childA.inferSlotType("localB", getNativeStringType());
+    FlowScope childABC = childAB.inferSlotType("localA", getNativeBooleanType());
+    FlowScope childB = childAB.inferSlotType("localB", getNativeStringType());
+    FlowScope childBC = childB.inferSlotType("localA", getNativeNoType());
 
     assertScopesSame(childAB, childB);
     assertScopesDiffer(childABC, childBC);
@@ -282,11 +190,8 @@ public void testDiffer1() {
   }
 
   public void testDiffer2() {
-    FlowScope childA = localEntry.createChildFlowScope();
-    childA = childA.inferSlotType("localA", getNativeNumberType());
-
-    FlowScope childB = localEntry.createChildFlowScope();
-    childB = childB.inferSlotType("localA", getNativeNoType());
+    FlowScope childA = localEntry.inferSlotType("localA", getNativeNumberType());
+    FlowScope childB = localEntry.inferSlotType("localA", getNativeNoType());
 
     assertScopesDiffer(childA, childB);
   }
diff --git a/test/com/google/javascript/jscomp/TypeInferenceTest.java b/test/com/google/javascript/jscomp/TypeInferenceTest.java
index d6d896746f5..454279da180 100644
--- a/test/com/google/javascript/jscomp/TypeInferenceTest.java
+++ b/test/com/google/javascript/jscomp/TypeInferenceTest.java
@@ -186,8 +186,7 @@ public void visit(NodeTraversal t, Node n, Node parent) {
         cfg.getImplicitReturn().getAnnotation();
     // Reset the flow scope's syntactic scope to the function block, rather than the function node
     // itself.  This allows pulling out local vars from the function by name to verify their types.
-    returnScope =
-        rtnState.getIn().createChildFlowScope(scopeCreator.createScope(n.getLastChild()));
+    returnScope = rtnState.getIn().withSyntacticScope(scopeCreator.createScope(n.getLastChild()));
   }
 
   private LabeledStatement getLabeledStatement(String label) {