diff --git a/eslint.config.mjs b/eslint.config.mjs
index e212547..b31bd3a 100644
--- a/eslint.config.mjs
+++ b/eslint.config.mjs
@@ -7,4 +7,9 @@ export default [
     ],
   },
   ...baseConfig,
+  {
+    rules: {
+      "unicorn/no-array-for-each": "off",
+    },
+  },
 ];
diff --git a/src/core/precompile.ts b/src/core/precompile.ts
index 2267c20..77b5562 100644
--- a/src/core/precompile.ts
+++ b/src/core/precompile.ts
@@ -61,38 +61,38 @@ export async function precompile(
     assert(matchedTestFiles.size > 0, "No matched testname");
   }
 
-  const sourceFunctions = new Map<string, SourceFunctionInfo[]>();
+  let sourceFunctions: Map<string, SourceFunctionInfo[]> | undefined = undefined;
   if (collectCoverage) {
     const sourceCodePaths = getRelatedFiles(includes, excludes, (path: string) => !path.endsWith(".test.ts"));
     const sourceTransformFunction = join(projectRoot, "transform", "listFunctions.mjs");
-    // The batchSize = 2 is empirical data after benchmarking
-    const batchSize = 2;
-    for (let i = 0; i < sourceCodePaths.length; i += batchSize) {
-      await Promise.all(
-        sourceCodePaths.slice(i, i + batchSize).map((sourcePath) =>
-          transform(sourceTransformFunction, sourcePath, flags, () => {
-            sourceFunctions.set(sourcePath, functionInfos);
-          })
-        )
-      );
-    }
+    globalThis.__functionInfos = undefined;
+    sourceFunctions = await transform(sourceTransformFunction, sourceCodePaths, flags, () => __functionInfos);
   }
-
   return {
     testCodePaths: matchedTestFiles.size > 0 ? Array.from(matchedTestFiles) : testCodePaths,
     matchedTestNames,
-    sourceFunctions,
+    sourceFunctions: sourceFunctions || new Map<string, SourceFunctionInfo[]>(),
   };
 }
 
-async function transform(transformFunction: string, codePath: string, flags: string, collectCallback: () => void) {
-  let ascArgv = [codePath, "--noEmit", "--disableWarning", "--transform", transformFunction, "-O0"];
+async function transform<T>(
+  transformFunction: string,
+  codePath: string | string[],
+  flags: string,
+  collectCallback: () => T
+) {
+  let ascArgv = ["--noEmit", "--disableWarning", "--transform", transformFunction, "-O0"];
+  if (typeof codePath === "string") {
+    ascArgv.push(codePath);
+  } else {
+    ascArgv.push(...codePath);
+  }
   if (flags) {
     const argv = flags.split(" ");
     ascArgv = ascArgv.concat(argv);
   }
   await ascMain(ascArgv, true);
-  collectCallback();
+  return collectCallback();
 }
 
 // a. include in config
diff --git a/src/parser/index.ts b/src/parser/index.ts
index 6872535..9dcfacb 100644
--- a/src/parser/index.ts
+++ b/src/parser/index.ts
@@ -77,7 +77,6 @@ export class Parser {
         this.functionCovTraceMap.set(name, originTraces.concat(traces));
       }
       const lineInfoMap: LineInfoMap = new Map();
-      // eslint-disable-next-line unicorn/no-array-for-each
       info.lineInfo.forEach((ranges: LineRange | null, index: number) => {
         // If instrument return basic block == null, ignore it.
         if (ranges === null) return;
diff --git a/src/type/global.d.ts b/src/type/global.d.ts
index c4caa07..4417f80 100644
--- a/src/type/global.d.ts
+++ b/src/type/global.d.ts
@@ -1,10 +1,13 @@
 import { SourceFunctionInfo } from "../interface.ts";
 
 declare global {
+  // why use var: [Remove block-scoped bindings from globalThis](https://github.com/microsoft/TypeScript/issues/30547)
   // store listFunctions transform results in global
-  let functionInfos: SourceFunctionInfo[];
+  // eslint-disable-next-line no-var
+  var __functionInfos: Map<string, SourceFunctionInfo[]> | undefined;
   // store listTestNames transform results in global
-  let testNames: string[];
+  // eslint-disable-next-line no-var
+  var testNames: string[];
 }
 
 export {};
diff --git a/transform/listFunctions.mts b/transform/listFunctions.mts
index 19c804d..d9e892f 100644
--- a/transform/listFunctions.mts
+++ b/transform/listFunctions.mts
@@ -62,12 +62,17 @@ class SourceFunctionTransform extends Transform {
   afterInitialize(program: Program) {
     this.#elementsByDeclaration = program.elementsByDeclaration;
     // There will be two sources with SourceKind.UserEntry, ~lib/rt/index-incremental.ts should be filtered
-    const entrySource = program.sources.find(
-      (source) => source.sourceKind === SourceKind.UserEntry && !source.normalizedPath.startsWith("~lib/")
-    );
-    this.visitNode(entrySource);
-    this.functionInfos.reverse();
-    globalThis.functionInfos = this.functionInfos;
+    program.sources
+      .filter((source) => source.sourceKind === SourceKind.UserEntry && !source.normalizedPath.startsWith("~lib/"))
+      .forEach((source) => {
+        this.functionInfos = [];
+        this.visitNode(source);
+        this.functionInfos.reverse();
+        const functionInfos =
+          (globalThis.__functionInfos as Map<string, SourceFunctionInfo[]>) || new Map<string, SourceFunctionInfo[]>();
+        functionInfos.set(source.normalizedPath, this.functionInfos);
+        globalThis.__functionInfos = functionInfos;
+      });
     throw new Error("TransformDone");
   }