diff --git a/lib/controllers/root-controller.js b/lib/controllers/root-controller.js
index bc49929d33..215770f173 100644
--- a/lib/controllers/root-controller.js
+++ b/lib/controllers/root-controller.js
@@ -23,6 +23,7 @@ import GitTabController from './git-tab-controller';
 import StatusBarTileController from './status-bar-tile-controller';
 import RepositoryConflictController from './repository-conflict-controller';
 import GithubLoginModel from '../models/github-login-model';
+import GitCacheView from '../views/git-cache-view';
 import Conflict from '../models/conflicts/conflict';
 import RefHolder from '../models/ref-holder';
 import Switchboard from '../switchboard';
@@ -115,6 +116,7 @@ export default class RootController extends React.Component {
         {devMode && <Command command="github:install-react-dev-tools" callback={this.installReactDevTools} />}
         <Command command="github:logout" callback={this.clearGithubToken} />
         <Command command="github:show-waterfall-diagnostics" callback={this.showWaterfallDiagnostics} />
+        <Command command="github:show-cache-diagnostics" callback={this.showCacheDiagnostics} />
         <Command command="github:open-issue-or-pull-request" callback={this.showOpenIssueishDialog} />
         <Command command="github:toggle-git-tab" callback={this.gitTabTracker.toggle} />
         <Command command="github:toggle-git-tab-focus" callback={this.gitTabTracker.toggleFocus} />
@@ -343,6 +345,9 @@ export default class RootController extends React.Component {
         <PaneItem workspace={this.props.workspace} uriPattern={GitTimingsView.uriPattern}>
           {({itemHolder}) => <GitTimingsView ref={itemHolder.setter} />}
         </PaneItem>
+        <PaneItem workspace={this.props.workspace} uriPattern={GitCacheView.uriPattern}>
+          {({itemHolder}) => <GitCacheView ref={itemHolder.setter} repository={this.props.repository} />}
+        </PaneItem>
       </Fragment>
     );
   }
@@ -404,6 +409,11 @@ export default class RootController extends React.Component {
     this.props.workspace.open(GitTimingsView.buildURI());
   }
 
+  @autobind
+  showCacheDiagnostics() {
+    this.props.workspace.open(GitCacheView.buildURI());
+  }
+
   @autobind
   async acceptClone(remoteUrl, projectPath) {
     this.setState({cloneDialogInProgress: true});
diff --git a/lib/models/branch-set.js b/lib/models/branch-set.js
index 94371cb033..afd8c41df0 100644
--- a/lib/models/branch-set.js
+++ b/lib/models/branch-set.js
@@ -1,3 +1,5 @@
+import util from 'util';
+
 import {nullBranch} from './branch';
 
 function pushAtKey(map, key, value) {
@@ -60,4 +62,8 @@ export default class BranchSet {
   getPushSources(remoteName, remoteRefName) {
     return this.byPushRef.get(`${remoteName}\0${remoteRefName}`) || [];
   }
+
+  [util.inspect.custom](depth, options) {
+    return `BranchSet {${util.inspect(this.all)}}`;
+  }
 }
diff --git a/lib/models/branch.js b/lib/models/branch.js
index aba10e3f20..2f7307cfee 100644
--- a/lib/models/branch.js
+++ b/lib/models/branch.js
@@ -1,3 +1,5 @@
+import util from 'util';
+
 const DETACHED = Symbol('detached');
 const REMOTE_TRACKING = Symbol('remote-tracking');
 
@@ -132,4 +134,8 @@ export const nullBranch = {
   isPresent() {
     return false;
   },
+
+  [util.inspect.custom](depth, options) {
+    return '{nullBranch}';
+  },
 };
diff --git a/lib/models/repository-states/present.js b/lib/models/repository-states/present.js
index 1342b6bf6b..4e02cf4f16 100644
--- a/lib/models/repository-states/present.js
+++ b/lib/models/repository-states/present.js
@@ -1,4 +1,5 @@
 import path from 'path';
+import {Emitter} from 'event-kit';
 import fs from 'fs-extra';
 
 import State from './state';
@@ -87,6 +88,11 @@ export default class Present extends State {
     return true;
   }
 
+  destroy() {
+    this.cache.destroy();
+    super.destroy();
+  }
+
   showStatusBarTiles() {
     return true;
   }
@@ -695,6 +701,11 @@ export default class Present extends State {
   getLastHistorySnapshots(partialDiscardFilePath = null) {
     return this.discardHistory.getLastSnapshots(partialDiscardFilePath);
   }
+
+  // Cache
+  getCache() {
+    return this.cache;
+  }
 }
 
 State.register(Present);
@@ -818,18 +829,25 @@ class Cache {
   constructor() {
     this.storage = new Map();
     this.byGroup = new Map();
+
+    this.emitter = new Emitter();
   }
 
   getOrSet(key, operation) {
     const primary = key.getPrimary();
     const existing = this.storage.get(primary);
     if (existing !== undefined) {
-      return existing;
+      existing.hits++;
+      return existing.promise;
     }
 
     const created = operation();
 
-    this.storage.set(primary, created);
+    this.storage.set(primary, {
+      createdAt: performance.now(),
+      hits: 0,
+      promise: created,
+    });
 
     const groups = key.getGroups();
     for (let i = 0; i < groups.length; i++) {
@@ -842,6 +860,8 @@ class Cache {
       groupSet.add(key);
     }
 
+    this.didUpdate();
+
     return created;
   }
 
@@ -849,6 +869,10 @@ class Cache {
     for (let i = 0; i < keys.length; i++) {
       keys[i].removeFromCache(this);
     }
+
+    if (keys.length > 0) {
+      this.didUpdate();
+    }
   }
 
   keysInGroup(group) {
@@ -857,16 +881,35 @@ class Cache {
 
   removePrimary(primary) {
     this.storage.delete(primary);
+    this.didUpdate();
   }
 
   removeFromGroup(group, key) {
     const groupSet = this.byGroup.get(group);
     groupSet && groupSet.delete(key);
+    this.didUpdate();
+  }
+
+  [Symbol.iterator]() {
+    return this.storage[Symbol.iterator]();
   }
 
   clear() {
     this.storage.clear();
     this.byGroup.clear();
+    this.didUpdate();
+  }
+
+  didUpdate() {
+    this.emitter.emit('did-update');
+  }
+
+  onDidUpdate(callback) {
+    return this.emitter.on('did-update', callback);
+  }
+
+  destroy() {
+    this.emitter.dispose();
   }
 }
 
diff --git a/lib/models/repository-states/state.js b/lib/models/repository-states/state.js
index 7008d2d246..6ac1a85cca 100644
--- a/lib/models/repository-states/state.js
+++ b/lib/models/repository-states/state.js
@@ -448,6 +448,13 @@ export default class State {
     return '';
   }
 
+  // Cache
+
+  @shouldDelegate
+  getCache() {
+    return null;
+  }
+
   // Internal //////////////////////////////////////////////////////////////////////////////////////////////////////////
   // Non-delegated methods that provide subclasses with convenient access to Repository properties.
 
diff --git a/lib/models/repository.js b/lib/models/repository.js
index 9bfc75b187..e09bac85cd 100644
--- a/lib/models/repository.js
+++ b/lib/models/repository.js
@@ -347,6 +347,7 @@ const delegates = [
 
   'setCommitMessage',
   'getCommitMessage',
+  'getCache',
 ];
 
 for (let i = 0; i < delegates.length; i++) {
diff --git a/lib/views/git-cache-view.js b/lib/views/git-cache-view.js
new file mode 100644
index 0000000000..0998b8ca85
--- /dev/null
+++ b/lib/views/git-cache-view.js
@@ -0,0 +1,216 @@
+import React from 'react';
+import PropTypes from 'prop-types';
+import {autobind} from 'core-decorators';
+import {inspect} from 'util';
+
+import ObserveModel from './observe-model';
+
+const sortOrders = {
+  'by key': (a, b) => a.key.localeCompare(b.key),
+  'oldest first': (a, b) => b.age - a.age,
+  'newest first': (a, b) => a.age - b.age,
+  'most hits': (a, b) => b.hits - a.hits,
+  'fewest hits': (a, b) => a.hits - b.hits,
+};
+
+export default class GitCacheView extends React.Component {
+  static uriPattern = 'atom-github://debug/cache'
+
+  static buildURI() {
+    return this.uriPattern;
+  }
+
+  static propTypes = {
+    repository: PropTypes.object.isRequired,
+  }
+
+  constructor(props, context) {
+    super(props, context);
+
+    this.state = {
+      order: 'by key',
+    };
+  }
+
+  getURI() {
+    return 'atom-github://debug/cache';
+  }
+
+  getTitle() {
+    return 'GitHub Package Cache View';
+  }
+
+  serialize() {
+    return null;
+  }
+
+  @autobind
+  fetchRepositoryData(repository) {
+    return repository.getCache();
+  }
+
+  @autobind
+  fetchCacheData(cache) {
+    const cached = {};
+    const promises = [];
+    const now = performance.now();
+
+    for (const [key, value] of cache) {
+      cached[key] = {
+        hits: value.hits,
+        age: now - value.createdAt,
+      };
+
+      promises.push(
+        value.promise
+          .then(
+            payload => inspect(payload, {depth: 3, breakLength: 30}),
+            err => `${err.message}\n${err.stack}`,
+          )
+          .then(resolved => { cached[key].value = resolved; }),
+      );
+    }
+
+    return Promise.all(promises).then(() => cached);
+  }
+
+  render() {
+    return (
+      <ObserveModel model={this.props.repository} fetchData={this.fetchRepositoryData}>
+        {cache => (
+          <ObserveModel model={cache} fetchData={this.fetchCacheData}>
+            {this.renderCache}
+          </ObserveModel>
+        )}
+      </ObserveModel>
+    );
+  }
+
+  @autobind
+  renderCache(contents) {
+    const rows = Object.keys(contents || {}).map(key => {
+      return {
+        key,
+        age: contents[key].age,
+        hits: contents[key].hits,
+        content: contents[key].value,
+      };
+    });
+
+    rows.sort(sortOrders[this.state.order]);
+
+    const orders = Object.keys(sortOrders);
+
+    return (
+      <div className="github-CacheView">
+        <header>
+          <h1>Cache contents</h1>
+          <p>
+            <span className="badge">{rows.length}</span> cached items
+          </p>
+        </header>
+        <main>
+          <p className="github-CacheView-Controls">
+            <span className="github-CacheView-Order">
+              order
+              <select
+                className="input-select"
+                onChange={this.didSelectItem}
+                value={this.state.order}>
+                {orders.map(order => {
+                  return <option key={order} value={order}>{order}</option>;
+                })}
+              </select>
+            </span>
+            <span className="github-CacheView-Clear">
+              <button className="btn icon icon-trashcan" onClick={this.clearCache}>
+                Clear
+              </button>
+            </span>
+          </p>
+          <table>
+            <thead>
+              <tr>
+                <td className="github-CacheView-Key">key</td>
+                <td className="github-CacheView-Age">age</td>
+                <td className="github-CacheView-Hits">hits</td>
+                <td className="github-CacheView-Content">content</td>
+              </tr>
+            </thead>
+            <tbody>
+              {rows.map(row => (
+                <tr key={row.key} className="github-CacheView-Row">
+                  <td className="github-CacheView-Key">
+                    <button className="btn" onClick={() => this.didClickKey(row.key)}>
+                      {row.key}
+                    </button>
+                  </td>
+                  <td className="github-CacheView-Age">
+                    {this.formatAge(row.age)}
+                  </td>
+                  <td className="github-CacheView-Hits">
+                    {row.hits}
+                  </td>
+                  <td className="github-CacheView-Content">
+                    <code>{row.content}</code>
+                  </td>
+                </tr>
+              ))}
+            </tbody>
+          </table>
+        </main>
+      </div>
+    );
+  }
+
+  formatAge(ageMs) {
+    let remaining = ageMs;
+    const parts = [];
+
+    if (remaining > 3600000) {
+      const hours = Math.floor(remaining / 3600000);
+      parts.push(`${hours}h`);
+      remaining -= (3600000 * hours);
+    }
+
+    if (remaining > 60000) {
+      const minutes = Math.floor(remaining / 60000);
+      parts.push(`${minutes}m`);
+      remaining -= (60000 * minutes);
+    }
+
+    if (remaining > 1000) {
+      const seconds = Math.floor(remaining / 1000);
+      parts.push(`${seconds}s`);
+      remaining -= (1000 * seconds);
+    }
+
+    parts.push(`${Math.floor(remaining)}ms`);
+
+    return parts.slice(parts.length - 2).join(' ');
+  }
+
+  @autobind
+  didSelectItem(event) {
+    this.setState({order: event.target.value});
+  }
+
+  didClickKey(key) {
+    const cache = this.props.repository.getCache();
+    if (!cache) {
+      return;
+    }
+
+    cache.removePrimary(key);
+  }
+
+  @autobind
+  clearCache() {
+    const cache = this.props.repository.getCache();
+    if (!cache) {
+      return;
+    }
+
+    cache.clear();
+  }
+}
diff --git a/styles/cache-view.less b/styles/cache-view.less
new file mode 100644
index 0000000000..0847e9aff5
--- /dev/null
+++ b/styles/cache-view.less
@@ -0,0 +1,64 @@
+@import "variables";
+
+.github-CacheView {
+  width: 100%;
+  height: 100%;
+  overflow-y: auto;
+
+  header {
+    text-align: center;
+    border-bottom: 1px solid @base-border-color;
+    padding: @component-padding;
+  }
+
+  &-Controls {
+    padding: 0 @component-padding;
+    text-align: right;
+  }
+
+  &-Clear {
+    margin-left: 1em;
+  }
+
+  &-Order select {
+    margin-left: 0.5em;
+  }
+
+  table {
+    margin: 10px 20px;
+    width: 90%;
+  }
+
+  thead {
+    color: @text-color-highlight;
+    background-color: @background-color-highlight;
+    font-weight: bold;
+  }
+
+  td {
+    padding: @component-padding / 2;
+    vertical-align: top;
+  }
+
+  &-Key {
+    button {
+      width: 100%;
+      font-family: monospace;
+      text-align: left;
+    }
+  }
+
+  &-Age {
+    min-width: 100px;
+  }
+
+  &-Hits {
+    min-width: 50px;
+  }
+
+  &-Content {
+    white-space: pre-wrap;
+    max-height: 100px;
+    overflow-y: scroll;
+  }
+}