diff --git a/src/lib/editorFile.js b/src/lib/editorFile.js
index c59127d03..b151fda80 100644
--- a/src/lib/editorFile.js
+++ b/src/lib/editorFile.js
@@ -1465,6 +1465,8 @@ export default class EditorFile {
 		// Store mode info for later use when creating editor view
 		this.currentMode = mode;
 		this.currentLanguageExtension = modeInfo?.getExtension() || null;
+		this.__cmCachedLanguageExtension = null;
+		this.__cmCachedLanguageSignature = null;
 		if (options.recommend !== false) {
 			maybeRecommendLanguageModeExtension(this, modeInfo);
 		}
diff --git a/src/lib/editorManager.js b/src/lib/editorManager.js
index 3a12f6184..84b905999 100644
--- a/src/lib/editorManager.js
+++ b/src/lib/editorManager.js
@@ -2709,6 +2709,8 @@ async function EditorManager($header, $body) {
 				effects: languageCompartment.reconfigure(ext || []),
 			});
 			file.session = targetEditor.state;
+			file.__cmCachedLanguageExtension = ext || [];
+			file.__cmCachedLanguageSignature = languageSignature;
 			markLanguageReady(file, languageSignature, true);
 		} catch (error) {
 			warnRecoverable("Failed to apply language extensions.", error, warnKey);
@@ -2722,6 +2724,14 @@ async function EditorManager($header, $body) {
 			return [];
 		}
 
+		if (
+			file.__cmCachedLanguageExtension &&
+			file.__cmCachedLanguageSignature === languageSignature
+		) {
+			markLanguageReady(file, languageSignature, true);
+			return file.__cmCachedLanguageExtension;
+		}
+
 		let result;
 		try {
 			result = langExtFn();
@@ -2735,12 +2745,13 @@ async function EditorManager($header, $body) {
 			markLanguageReady(file, languageSignature, false);
 			result
 				.then((ext) => {
+					if (file.__cmLanguageSignature !== languageSignature) {
+						return;
+					}
+					file.__cmCachedLanguageExtension = ext || [];
+					file.__cmCachedLanguageSignature = languageSignature;
 					const pane = getFileLspPane(file);
-					if (
-						!pane?.editor ||
-						pane.activeFile?.id !== fileId ||
-						file.__cmLanguageSignature !== languageSignature
-					) {
+					if (!pane?.editor || pane.activeFile?.id !== fileId) {
 						return;
 					}
 
@@ -2759,6 +2770,8 @@ async function EditorManager($header, $body) {
 		}
 
 		markLanguageReady(file, languageSignature, true);
+		file.__cmCachedLanguageExtension = result || [];
+		file.__cmCachedLanguageSignature = languageSignature;
 		return result || [];
 	}