Fix performance regressions with lazy symbol caching

- Replace eager symbol pre-computation with lazy caching
- Fix inconsistency between cached and Symbol.for() usage
- Update outerClosureStatements to use Symbol.for() in generated code
- Update fast-instantiator to use Symbol.for() consistently
- Maintain symbol caching benefits while eliminating instantiation overhead

Co-Authored-By: Harry Brundage <[email protected]>

Author: devin-ai-integration[bot]

src/fast-getter.ts

@@ -28,26 +28,32 @@ export class FastGetBuilder {
 
     this.memoSymbols = new Map();
     this.snapshotSymbols = new Map();
-    for (const property of this.memoizableProperties) {
-      this.memoSymbols.set(property, Symbol.for(this.memoSymbolName(property)));
-      this.snapshotSymbols.set(property, Symbol.for(this.snapshottedViewInputSymbolName(property)));
-    }
   }
 
   memoSymbolName(property: string) {
     return `mqt/${property}-memo`;
   }
 
   getMemoSymbol(property: string) {
-    return this.memoSymbols.get(property)!;
+    let symbol = this.memoSymbols.get(property);
+    if (!symbol) {
+      symbol = Symbol.for(this.memoSymbolName(property));
+      this.memoSymbols.set(property, symbol);
+    }
+    return symbol;
   }
 
   snapshottedViewInputSymbolName(property: string) {
     return `mqt/${property}-svi-memo`;
   }
 
   getSnapshotSymbol(property: string) {
-    return this.snapshotSymbols.get(property)!;
+    let symbol = this.snapshotSymbols.get(property);
+    if (!symbol) {
+      symbol = Symbol.for(this.snapshottedViewInputSymbolName(property));
+      this.snapshotSymbols.set(property, symbol);
+    }
+    return symbol;
   }
 
   outerClosureStatements(className: string) {