diff --git a/lib/NormalModule.js b/lib/NormalModule.js
index 6605cb86734..71ffe6533da 100644
--- a/lib/NormalModule.js
+++ b/lib/NormalModule.js
@@ -276,6 +276,8 @@ class NormalModule extends Module {
 		this._source = null;
 		/** @private @type {Map<string, number> | undefined} **/
 		this._sourceSizes = undefined;
+		/** @private @type {Set<string>} */
+		this._sourceTypes = undefined;
 
 		// Cache
 		this._lastSuccessfulBuildMeta = {};
@@ -347,12 +349,19 @@ class NormalModule extends Module {
 		this.resource = m.resource;
 		this.matchResource = m.matchResource;
 		this.loaders = m.loaders;
+		this._sourceTypes = m._sourceTypes;
+		this._sourceSizes = m._sourceSizes;
 	}
 
 	/**
 	 * Assuming this module is in the cache. Remove internal references to allow freeing some memory.
 	 */
 	cleanupForCache() {
+		// Make sure to cache types and sizes before cleanup
+		if (this._sourceTypes === undefined) this.getSourceTypes();
+		for (const type of this._sourceTypes) {
+			this.size(type);
+		}
 		super.cleanupForCache();
 		this.parser = undefined;
 		this.parserOptions = undefined;
@@ -390,6 +399,7 @@ class NormalModule extends Module {
 			this.type,
 			this.generatorOptions
 		);
+		// we assume the generator behaves identically and keep cached sourceTypes/Sizes
 	}
 
 	/**
@@ -873,6 +883,7 @@ class NormalModule extends Module {
 		this._forceBuild = false;
 		this._source = null;
 		if (this._sourceSizes !== undefined) this._sourceSizes.clear();
+		this._sourceTypes = undefined;
 		this._ast = null;
 		this.error = null;
 		this.clearWarningsAndErrors();
@@ -1075,7 +1086,10 @@ class NormalModule extends Module {
 	 * @returns {Set<string>} types available (do not mutate)
 	 */
 	getSourceTypes() {
-		return this.generator.getTypes(this);
+		if (this._sourceTypes === undefined) {
+			this._sourceTypes = this.generator.getTypes(this);
+		}
+		return this._sourceTypes;
 	}
 
 	/**
@@ -1264,7 +1278,6 @@ class NormalModule extends Module {
 		const { write } = context;
 		// deserialize
 		write(this._source);
-		write(this._sourceSizes);
 		write(this.error);
 		write(this._lastSuccessfulBuildMeta);
 		write(this._forceBuild);
@@ -1296,7 +1309,6 @@ class NormalModule extends Module {
 	deserialize(context) {
 		const { read } = context;
 		this._source = read();
-		this._sourceSizes = read();
 		this.error = read();
 		this._lastSuccessfulBuildMeta = read();
 		this._forceBuild = read();
diff --git a/test/Compiler.test.js b/test/Compiler.test.js
index 35e6f63c507..9f8903cac75 100644
--- a/test/Compiler.test.js
+++ b/test/Compiler.test.js
@@ -467,11 +467,12 @@ describe("Compiler", () => {
 			}
 		});
 		compiler.outputFileSystem = createFsFromVolume(new Volume());
-		compiler.run((err, stats) => {
+		compiler.run((err, stats1) => {
 			if (err) return done(err);
 
-			compiler.run((err, stats) => {
+			compiler.run((err, stats2) => {
 				if (err) return done(err);
+				expect(stats1.toString({ all: true })).toBeTypeOf("string");
 				done();
 			});
 		});
diff --git a/test/WatchTestCases.test.js b/test/WatchTestCases.test.js
index cb30887f2bf..2e21996f02a 100644
--- a/test/WatchTestCases.test.js
+++ b/test/WatchTestCases.test.js
@@ -169,10 +169,11 @@ describe("WatchTestCases", () => {
 									},
 									(err, stats) => {
 										if (err) return compilationFinished(err);
-										if (!stats)
+										if (!stats) {
 											return compilationFinished(
 												new Error("No stats reported from Compiler")
 											);
+										}
 										if (stats.hash === lastHash) return;
 										lastHash = stats.hash;
 										if (run.done && lastHash !== stats.hash) {
@@ -192,6 +193,7 @@ describe("WatchTestCases", () => {
 										}
 										if (waitMode) return;
 										run.done = true;
+										run.stats = stats;
 										if (err) return compilationFinished(err);
 										const statOptions = {
 											preset: "verbose",
@@ -383,6 +385,10 @@ describe("WatchTestCases", () => {
 						);
 						run.it = _it;
 						run.getNumberOfTests = getNumberOfTests;
+						it(`${run.name} should allow to read stats`, done => {
+							if (run.stats) run.stats.toString({ all: true });
+							done();
+						});
 					}
 
 					afterAll(() => {