diff --git a/examples/browser/cql4browsers.js b/examples/browser/cql4browsers.js
index b969ee81..3aac8549 100644
--- a/examples/browser/cql4browsers.js
+++ b/examples/browser/cql4browsers.js
@@ -6811,21 +6811,50 @@ class FunctionRef extends expression_1.Expression {
         super(json);
         this.name = json.name;
         this.library = json.libraryName;
+        this.functionDefs = null;
     }
     async exec(ctx) {
-        let functionDefs, child_ctx;
+        const args = await this.execArgs(ctx);
+        // Filter out functions w/ wrong number of arguments.
+        const fDefs = this.getFunctionDefs(ctx, args);
+        // If there is still > 1 matching function, calculate a score based on quality of matches
+        if (fDefs.length > 1) {
+            // TODO
+        }
+        if (fDefs.length === 0) {
+            throw new Error('no function with matching signature could be found');
+        }
+        // Moved context creation below the functionDef checks because it's not needed if
+        // there are no matching function defs
+        let child_ctx;
         if (this.library) {
-            const lib = ctx.get(this.library);
-            functionDefs = lib ? lib.getFunction(this.name) : undefined;
             const libCtx = ctx.getLibraryContext(this.library);
             child_ctx = libCtx ? libCtx.childContext() : undefined;
         }
         else {
-            functionDefs = ctx.get(this.name);
             child_ctx = ctx.childContext();
         }
-        const args = await this.execArgs(ctx);
-        // Filter out functions w/ wrong number of arguments.
+        // By this point, we should have only one function, but until implementation is completed,
+        // use the last one (no matter how many still remain)
+        const functionDef = fDefs[fDefs.length - 1];
+        for (let i = 0; i < functionDef.parameters.length; i++) {
+            child_ctx.set(functionDef.parameters[i].name, args[i]);
+        }
+        return functionDef.expression.execute(child_ctx);
+    }
+    getFunctionDefs(ctx, args) {
+        if (this.functionDefs != null) {
+            // cache hit
+            return this.functionDefs;
+        }
+        let functionDefs;
+        if (this.library) {
+            const lib = ctx.get(this.library);
+            functionDefs = lib ? lib.getFunction(this.name) : undefined;
+        }
+        else {
+            functionDefs = ctx.get(this.name);
+        }
         functionDefs = functionDefs.filter((f) => f.parameters.length === args.length);
         // If there is still > 1 matching function, filter by argument types
         if (functionDefs.length > 1) {
@@ -6847,20 +6876,8 @@ class FunctionRef extends expression_1.Expression {
                 return match;
             });
         }
-        // If there is still > 1 matching function, calculate a score based on quality of matches
-        if (functionDefs.length > 1) {
-            // TODO
-        }
-        if (functionDefs.length === 0) {
-            throw new Error('no function with matching signature could be found');
-        }
-        // By this point, we should have only one function, but until implementation is completed,
-        // use the last one (no matter how many still remain)
-        const functionDef = functionDefs[functionDefs.length - 1];
-        for (let i = 0; i < functionDef.parameters.length; i++) {
-            child_ctx.set(functionDef.parameters[i].name, args[i]);
-        }
-        return functionDef.expression.execute(child_ctx);
+        this.functionDefs = functionDefs;
+        return functionDefs;
     }
 }
 exports.FunctionRef = FunctionRef;
diff --git a/src/elm/reusable.ts b/src/elm/reusable.ts
index 2dfe6b01..57800827 100644
--- a/src/elm/reusable.ts
+++ b/src/elm/reusable.ts
@@ -59,27 +59,58 @@ export class FunctionDef extends Expression {
 export class FunctionRef extends Expression {
   name: string;
   library: string;
+  functionDefs: FunctionDef[] | null;
 
   constructor(json: any) {
     super(json);
     this.name = json.name;
     this.library = json.libraryName;
+    this.functionDefs = null;
   }
 
   async exec(ctx: Context) {
-    let functionDefs, child_ctx;
+    const args = await this.execArgs(ctx);
+    // Filter out functions w/ wrong number of arguments.
+    const fDefs = this.getFunctionDefs(ctx, args);
+    // If there is still > 1 matching function, calculate a score based on quality of matches
+    if (fDefs.length > 1) {
+      // TODO
+    }
+
+    if (fDefs.length === 0) {
+      throw new Error('no function with matching signature could be found');
+    }
+    // Moved context creation below the functionDef checks because it's not needed if
+    // there are no matching function defs
+    let child_ctx;
     if (this.library) {
-      const lib = ctx.get(this.library);
-      functionDefs = lib ? lib.getFunction(this.name) : undefined;
       const libCtx = ctx.getLibraryContext(this.library);
       child_ctx = libCtx ? libCtx.childContext() : undefined;
     } else {
-      functionDefs = ctx.get(this.name);
       child_ctx = ctx.childContext();
     }
-    const args = await this.execArgs(ctx);
+    // By this point, we should have only one function, but until implementation is completed,
+    // use the last one (no matter how many still remain)
+    const functionDef = fDefs[fDefs.length - 1];
+    for (let i = 0; i < functionDef.parameters.length; i++) {
+      child_ctx.set(functionDef.parameters[i].name, args[i]);
+    }
+    return functionDef.expression.execute(child_ctx);
+  }
+
+  getFunctionDefs(ctx: Context, args: any) {
+    if (this.functionDefs != null) {
+      // cache hit
+      return this.functionDefs;
+    }
+    let functionDefs;
+    if (this.library) {
+      const lib = ctx.get(this.library);
+      functionDefs = lib ? lib.getFunction(this.name) : undefined;
+    } else {
+      functionDefs = ctx.get(this.name);
+    }
 
-    // Filter out functions w/ wrong number of arguments.
     functionDefs = functionDefs.filter((f: any) => f.parameters.length === args.length);
     // If there is still > 1 matching function, filter by argument types
     if (functionDefs.length > 1) {
@@ -101,21 +132,8 @@ export class FunctionRef extends Expression {
         return match;
       });
     }
-    // If there is still > 1 matching function, calculate a score based on quality of matches
-    if (functionDefs.length > 1) {
-      // TODO
-    }
-
-    if (functionDefs.length === 0) {
-      throw new Error('no function with matching signature could be found');
-    }
-    // By this point, we should have only one function, but until implementation is completed,
-    // use the last one (no matter how many still remain)
-    const functionDef = functionDefs[functionDefs.length - 1];
-    for (let i = 0; i < functionDef.parameters.length; i++) {
-      child_ctx.set(functionDef.parameters[i].name, args[i]);
-    }
-    return functionDef.expression.execute(child_ctx);
+    this.functionDefs = functionDefs;
+    return functionDefs;
   }
 }