diff --git a/java/src/com/android/inputmethod/latin/BinaryDictionary.java b/java/src/com/android/inputmethod/latin/BinaryDictionary.java
index 931f98a..2fece7c 100644
--- a/java/src/com/android/inputmethod/latin/BinaryDictionary.java
+++ b/java/src/com/android/inputmethod/latin/BinaryDictionary.java
@@ -292,6 +292,7 @@
                 settingsValuesForSuggestion.mSpaceAwareGestureEnabled);
         session.mNativeSuggestOptions.setAdditionalFeaturesOptions(
                 settingsValuesForSuggestion.mAdditionalFeaturesSettingValues);
+        session.mNativeSuggestOptions.setWeightForLocale(weightForLocale);
         if (inOutWeightOfLangModelVsSpatialModel != null) {
             session.mInputOutputWeightOfLangModelVsSpatialModel[0] =
                     inOutWeightOfLangModelVsSpatialModel[0];
diff --git a/java/src/com/android/inputmethod/latin/settings/NativeSuggestOptions.java b/java/src/com/android/inputmethod/latin/settings/NativeSuggestOptions.java
index 31a20c4..7603dbb 100644
--- a/java/src/com/android/inputmethod/latin/settings/NativeSuggestOptions.java
+++ b/java/src/com/android/inputmethod/latin/settings/NativeSuggestOptions.java
@@ -22,7 +22,8 @@
     private static final int USE_FULL_EDIT_DISTANCE = 1;
     private static final int BLOCK_OFFENSIVE_WORDS = 2;
     private static final int SPACE_AWARE_GESTURE_ENABLED = 3;
-    private static final int OPTIONS_SIZE = 4;
+    private static final int WEIGHT_FOR_LOCALE_IN_THOUSANDS = 4;
+    private static final int OPTIONS_SIZE = 5;
 
     private final int[] mOptions = new int[OPTIONS_SIZE
             + AdditionalFeaturesSettingUtils.ADDITIONAL_FEATURES_SETTINGS_SIZE];
@@ -43,6 +44,12 @@
         setBooleanOption(SPACE_AWARE_GESTURE_ENABLED, value);
     }
 
+    public void setWeightForLocale(final float value) {
+        // We're passing this option as a fixed point value, in thousands. This is decoded in
+        // native code by SuggestOptions#weightForLocale().
+        setIntegerOption(WEIGHT_FOR_LOCALE_IN_THOUSANDS, (int) (value * 1000));
+    }
+
     public void setAdditionalFeaturesOptions(final int[] additionalOptions) {
         if (additionalOptions == null) {
             return;
diff --git a/native/jni/src/suggest/core/policy/traversal.h b/native/jni/src/suggest/core/policy/traversal.h
index 6dfa7e3..5b6616d 100644
--- a/native/jni/src/suggest/core/policy/traversal.h
+++ b/native/jni/src/suggest/core/policy/traversal.h
@@ -44,7 +44,7 @@
     virtual bool needsToTraverseAllUserInput() const = 0;
     virtual float getMaxSpatialDistance() const = 0;
     virtual int getDefaultExpandDicNodeSize() const = 0;
-    virtual int getMaxCacheSize(const int inputSize) const = 0;
+    virtual int getMaxCacheSize(const int inputSize, const float weightForLocale) const = 0;
     virtual int getTerminalCacheSize() const = 0;
     virtual bool isPossibleOmissionChildNode(const DicTraverseSession *const traverseSession,
             const DicNode *const parentDicNode, const DicNode *const dicNode) const = 0;
diff --git a/native/jni/src/suggest/core/suggest.cpp b/native/jni/src/suggest/core/suggest.cpp
index 457414f..cf2df86 100644
--- a/native/jni/src/suggest/core/suggest.cpp
+++ b/native/jni/src/suggest/core/suggest.cpp
@@ -28,6 +28,7 @@
 #include "suggest/core/policy/weighting.h"
 #include "suggest/core/result/suggestions_output_utils.h"
 #include "suggest/core/session/dic_traverse_session.h"
+#include "suggest/core/suggest_options.h"
 
 namespace latinime {
 
@@ -88,7 +89,8 @@
         traverseSession->getDicTraverseCache()->continueSearch();
     } else {
         // Restart recognition at the root.
-        traverseSession->resetCache(TRAVERSAL->getMaxCacheSize(traverseSession->getInputSize()),
+        traverseSession->resetCache(TRAVERSAL->getMaxCacheSize(traverseSession->getInputSize(),
+                traverseSession->getSuggestOptions()->weightForLocale()),
                 TRAVERSAL->getTerminalCacheSize());
         // Create a new dic node here
         DicNode rootNode;
diff --git a/native/jni/src/suggest/core/suggest_options.h b/native/jni/src/suggest/core/suggest_options.h
index d456680..4d33129 100644
--- a/native/jni/src/suggest/core/suggest_options.h
+++ b/native/jni/src/suggest/core/suggest_options.h
@@ -42,6 +42,12 @@
         return getBoolOption(SPACE_AWARE_GESTURE_ENABLED);
     }
 
+    AK_FORCE_INLINE float weightForLocale() const {
+        // The weight is in thousands and we want the real value, so we divide by 1000.
+        // NativeSuggestOptions#setWeightForLocale does the opposite processing in Java.
+        return static_cast<float>(getIntOption(WEIGHT_FOR_LOCALE_IN_THOUSANDS)) / 1000.0f;
+    }
+
     AK_FORCE_INLINE bool getAdditionalFeaturesBoolOption(const int key) const {
         return getBoolOption(key + ADDITIONAL_FEATURES_OPTIONS);
     }
@@ -55,9 +61,10 @@
     static const int USE_FULL_EDIT_DISTANCE = 1;
     static const int BLOCK_OFFENSIVE_WORDS = 2;
     static const int SPACE_AWARE_GESTURE_ENABLED = 3;
+    static const int WEIGHT_FOR_LOCALE_IN_THOUSANDS = 4;
     // Additional features options are stored after the other options and used as setting values of
     // experimental features.
-    static const int ADDITIONAL_FEATURES_OPTIONS = 4;
+    static const int ADDITIONAL_FEATURES_OPTIONS = 5;
 
     const int *const mOptions;
     const int mLength;
diff --git a/native/jni/src/suggest/policyimpl/typing/scoring_params.cpp b/native/jni/src/suggest/policyimpl/typing/scoring_params.cpp
index 3fc566e..b621eef 100644
--- a/native/jni/src/suggest/policyimpl/typing/scoring_params.cpp
+++ b/native/jni/src/suggest/policyimpl/typing/scoring_params.cpp
@@ -31,6 +31,7 @@
 // TODO: Unlimit max cache dic node size
 const int ScoringParams::MAX_CACHE_DIC_NODE_SIZE = 170;
 const int ScoringParams::MAX_CACHE_DIC_NODE_SIZE_FOR_SINGLE_POINT = 310;
+const int ScoringParams::MAX_CACHE_DIC_NODE_SIZE_FOR_LOW_PROBABILITY_LOCALE = 50;
 const int ScoringParams::THRESHOLD_SHORT_WORD_LENGTH = 4;
 
 const float ScoringParams::DISTANCE_WEIGHT_LENGTH = 0.1524f;
@@ -61,4 +62,7 @@
 const float ScoringParams::TYPING_BASE_OUTPUT_SCORE = 1.0f;
 const float ScoringParams::TYPING_MAX_OUTPUT_SCORE_PER_INPUT = 0.1f;
 const float ScoringParams::NORMALIZED_SPATIAL_DISTANCE_THRESHOLD_FOR_EDIT = 0.095f;
+const float ScoringParams::LOCALE_WEIGHT_THRESHOLD_FOR_SPACE_SUBSTITUTION = 0.99f;
+const float ScoringParams::LOCALE_WEIGHT_THRESHOLD_FOR_SPACE_OMISSION = 0.99f;
+const float ScoringParams::LOCALE_WEIGHT_THRESHOLD_FOR_SMALL_CACHE_SIZE = 0.99f;
 } // namespace latinime
diff --git a/native/jni/src/suggest/policyimpl/typing/scoring_params.h b/native/jni/src/suggest/policyimpl/typing/scoring_params.h
index b12de6d..731424f 100644
--- a/native/jni/src/suggest/policyimpl/typing/scoring_params.h
+++ b/native/jni/src/suggest/policyimpl/typing/scoring_params.h
@@ -30,6 +30,7 @@
     static const float AUTOCORRECT_OUTPUT_THRESHOLD;
     static const int MAX_CACHE_DIC_NODE_SIZE;
     static const int MAX_CACHE_DIC_NODE_SIZE_FOR_SINGLE_POINT;
+    static const int MAX_CACHE_DIC_NODE_SIZE_FOR_LOW_PROBABILITY_LOCALE;
     static const int THRESHOLD_SHORT_WORD_LENGTH;
 
     static const float EXACT_MATCH_PROMOTION;
@@ -68,6 +69,9 @@
     static const float TYPING_BASE_OUTPUT_SCORE;
     static const float TYPING_MAX_OUTPUT_SCORE_PER_INPUT;
     static const float NORMALIZED_SPATIAL_DISTANCE_THRESHOLD_FOR_EDIT;
+    static const float LOCALE_WEIGHT_THRESHOLD_FOR_SPACE_SUBSTITUTION;
+    static const float LOCALE_WEIGHT_THRESHOLD_FOR_SPACE_OMISSION;
+    static const float LOCALE_WEIGHT_THRESHOLD_FOR_SMALL_CACHE_SIZE;
 
  private:
     DISALLOW_IMPLICIT_CONSTRUCTORS(ScoringParams);
diff --git a/native/jni/src/suggest/policyimpl/typing/typing_traversal.h b/native/jni/src/suggest/policyimpl/typing/typing_traversal.h
index b64ee8b..b9b6314 100644
--- a/native/jni/src/suggest/policyimpl/typing/typing_traversal.h
+++ b/native/jni/src/suggest/policyimpl/typing/typing_traversal.h
@@ -26,6 +26,7 @@
 #include "suggest/core/layout/proximity_info_utils.h"
 #include "suggest/core/policy/traversal.h"
 #include "suggest/core/session/dic_traverse_session.h"
+#include "suggest/core/suggest_options.h"
 #include "suggest/policyimpl/typing/scoring_params.h"
 #include "utils/char_utils.h"
 
@@ -77,6 +78,13 @@
         if (!CORRECT_NEW_WORD_SPACE_SUBSTITUTION) {
             return false;
         }
+        if (traverseSession->getSuggestOptions()->weightForLocale()
+                < ScoringParams::LOCALE_WEIGHT_THRESHOLD_FOR_SPACE_SUBSTITUTION) {
+            // Space substitution is heavy, so we skip doing it if the weight for this language
+            // is low because we anticipate the suggestions out of this dictionary are not for
+            // the language the user intends to type in.
+            return false;
+        }
         if (!canDoLookAheadCorrection(traverseSession, dicNode)) {
             return false;
         }
@@ -91,6 +99,13 @@
         if (!CORRECT_NEW_WORD_SPACE_OMISSION) {
             return false;
         }
+        if (traverseSession->getSuggestOptions()->weightForLocale()
+                < ScoringParams::LOCALE_WEIGHT_THRESHOLD_FOR_SPACE_OMISSION) {
+            // Space omission is heavy, so we skip doing it if the weight for this language
+            // is low because we anticipate the suggestions out of this dictionary are not for
+            // the language the user intends to type in.
+            return false;
+        }
         const int inputSize = traverseSession->getInputSize();
         // TODO: Don't refer to isCompletion?
         if (dicNode->isCompletion(inputSize)) {
@@ -141,9 +156,14 @@
         return DicNodeVector::DEFAULT_NODES_SIZE_FOR_OPTIMIZATION;
     }
 
-    AK_FORCE_INLINE int getMaxCacheSize(const int inputSize) const {
-        return (inputSize <= 1) ? ScoringParams::MAX_CACHE_DIC_NODE_SIZE_FOR_SINGLE_POINT
-                : ScoringParams::MAX_CACHE_DIC_NODE_SIZE;
+    AK_FORCE_INLINE int getMaxCacheSize(const int inputSize, const float weightForLocale) const {
+        if (inputSize <= 1) {
+            return ScoringParams::MAX_CACHE_DIC_NODE_SIZE_FOR_SINGLE_POINT;
+        }
+        if (weightForLocale < ScoringParams::LOCALE_WEIGHT_THRESHOLD_FOR_SMALL_CACHE_SIZE) {
+            return ScoringParams::MAX_CACHE_DIC_NODE_SIZE_FOR_LOW_PROBABILITY_LOCALE;
+        }
+        return ScoringParams::MAX_CACHE_DIC_NODE_SIZE;
     }
 
     AK_FORCE_INLINE int getTerminalCacheSize() const {