perf(ui): optimize text buffer and highlighting for large inputs (#16782)

Co-authored-by: Jacob Richman <jacob314@gmail.com>

packages/core/src/utils/LruCache.ts

@@ -4,34 +4,24 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
+import { LRUMap } from 'mnemonist';
+
 export class LruCache<K, V> {
-  private cache: Map<K, V>;
-  private maxSize: number;
+  private cache: LRUMap<K, V>;
 
   constructor(maxSize: number) {
-    this.cache = new Map<K, V>();
-    this.maxSize = maxSize;
+    this.cache = new LRUMap<K, V>(maxSize);
   }
 
   get(key: K): V | undefined {
-    const value = this.cache.get(key);
-    if (value) {
-      // Move to end to mark as recently used
-      this.cache.delete(key);
-      this.cache.set(key, value);
-    }
-    return value;
+    return this.cache.get(key);
+  }
+
+  has(key: K): boolean {
+    return this.cache.has(key);
   }
 
   set(key: K, value: V): void {
-    if (this.cache.has(key)) {
-      this.cache.delete(key);
-    } else if (this.cache.size >= this.maxSize) {
-      const firstKey = this.cache.keys().next().value;
-      if (firstKey !== undefined) {
-        this.cache.delete(firstKey);
-      }
-    }
     this.cache.set(key, value);
   }