diff --git a/python/core/auto_generated/qgsvectorlayercache.sip.in b/python/core/auto_generated/qgsvectorlayercache.sip.in
index 4049ccf1fa72..5f4d41c5479c 100644
--- a/python/core/auto_generated/qgsvectorlayercache.sip.in
+++ b/python/core/auto_generated/qgsvectorlayercache.sip.in
@@ -11,7 +11,6 @@
 
 
 
-
 class QgsVectorLayerCache : QObject
 {
 %Docstring
diff --git a/src/core/qgsvectorlayercache.cpp b/src/core/qgsvectorlayercache.cpp
index 0dc790dec76c..43021874b317 100644
--- a/src/core/qgsvectorlayercache.cpp
+++ b/src/core/qgsvectorlayercache.cpp
@@ -175,7 +175,17 @@ bool QgsVectorLayerCache::removeCachedFeature( QgsFeatureId fid )
 {
   bool removed = mCache.remove( fid );
   if ( removed )
-    mCacheOrderedKeys.removeOne( fid );
+  {
+    auto unorderedIt = std::find( mCacheUnorderedKeys.begin(), mCacheUnorderedKeys.end(), fid );
+    if ( unorderedIt != mCacheUnorderedKeys.end() )
+    {
+      mCacheUnorderedKeys.erase( unorderedIt );
+
+      auto orderedIt = std::find( mCacheOrderedKeys.begin(), mCacheOrderedKeys.end(), fid );
+      if ( orderedIt != mCacheOrderedKeys.end() )
+        mCacheOrderedKeys.erase( orderedIt );
+    }
+  }
   return removed;
 }
 
@@ -268,7 +278,15 @@ void QgsVectorLayerCache::onJoinAttributeValueChanged( QgsFeatureId fid, int fie
 void QgsVectorLayerCache::featureDeleted( QgsFeatureId fid )
 {
   mCache.remove( fid );
-  mCacheOrderedKeys.removeOne( fid );
+
+  auto it = mCacheUnorderedKeys.find( fid );
+  if ( it != mCacheUnorderedKeys.end() )
+  {
+    mCacheUnorderedKeys.erase( it );
+    auto orderedIt = std::find( mCacheOrderedKeys.begin(), mCacheOrderedKeys.end(), fid );
+    if ( orderedIt != mCacheOrderedKeys.end() )
+      mCacheOrderedKeys.erase( orderedIt );
+  }
 }
 
 void QgsVectorLayerCache::onFeatureAdded( QgsFeatureId fid )
@@ -328,6 +346,7 @@ void QgsVectorLayerCache::invalidate()
 {
   mCache.clear();
   mCacheOrderedKeys.clear();
+  mCacheUnorderedKeys.clear();
   mFullCache = false;
   emit invalidated();
 }
diff --git a/src/core/qgsvectorlayercache.h b/src/core/qgsvectorlayercache.h
index 19981f5b9d4f..a2458daff41c 100644
--- a/src/core/qgsvectorlayercache.h
+++ b/src/core/qgsvectorlayercache.h
@@ -24,7 +24,8 @@
 #include "qgsfield.h"
 #include "qgsfeaturerequest.h"
 #include "qgsfeatureiterator.h"
-
+#include <unordered_set>
+#include <deque>
 #include <QCache>
 
 class QgsVectorLayer;
@@ -393,12 +394,20 @@ class CORE_EXPORT QgsVectorLayerCache : public QObject
     {
       QgsCachedFeature *cachedFeature = new QgsCachedFeature( feat, this );
       mCache.insert( feat.id(), cachedFeature );
-      if ( !mCacheOrderedKeys.contains( feat.id() ) )
+      if ( mCacheUnorderedKeys.find( feat.id() ) == mCacheUnorderedKeys.end() )
+      {
+        mCacheUnorderedKeys.insert( feat.id() );
         mCacheOrderedKeys << feat.id();
+      }
     }
 
     QgsVectorLayer *mLayer = nullptr;
     QCache< QgsFeatureId, QgsCachedFeature > mCache;
+
+    // we need two containers here. One is used for efficient tracking of the IDs which have been added to the cache, the other
+    // is used to store the order of the incoming feature ids, so that we can correctly iterate through features in the original order.
+    // the ordered list alone is far too slow to handle this -- searching for existing items in a list is magnitudes slower than the unordered_set
+    std::unordered_set< QgsFeatureId > mCacheUnorderedKeys;
     QList< QgsFeatureId > mCacheOrderedKeys;
 
     bool mCacheGeometry = true;