use Collator.compare in place of localeCompare

src/lib/blocks.js

@@ -246,10 +246,7 @@ export default function (vm) {
                     lookupBlocks = vm.runtime.flyoutBlocks;
                 }
                 const sort = function (options) {
-                    options.sort((str1, str2) => str1.localeCompare(str2, [], {
-                        sensitivity: 'base',
-                        numeric: true
-                    }));
+                    options.sort(ScratchBlocks.scratchBlocksUtils.compareStrings);
                 };
                 // Get all the stage variables (no lists) so we can add them to menu when the stage is selected.
                 const stageVariableOptions = vm.runtime.getTargetForStage().getAllVariableNamesInScopeByType('');
@@ -323,5 +320,16 @@ export default function (vm) {
         vm.runtime.emit('PLAY_NOTE', noteNum, extensionId);
     };
 
+    // Use a collator's compare instead of localeCompare which internally
+    // creates a collator. Using this is a lot faster in browsers that create a
+    // collator for every localeCompare call.
+    const collator = new Intl.Collator([], {
+        sensitivity: 'base',
+        numeric: true
+    });
+    ScratchBlocks.scratchBlocksUtils.compareStrings = function (str1, str2) {
+        return collator.compare(str1, str2);
+    };
+
     return ScratchBlocks;
 }