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diff --git a/app/assets/javascripts/repository/mixins/highlight_mixin.js b/app/assets/javascripts/repository/mixins/highlight_mixin.js
new file mode 100644
index 00000000000..95d0c55bb04
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+++ b/app/assets/javascripts/repository/mixins/highlight_mixin.js
@@ -0,0 +1,106 @@
+import { nextTick } from 'vue';
+import {
+  LEGACY_FALLBACKS,
+  EVENT_ACTION,
+  EVENT_LABEL_FALLBACK,
+  LINES_PER_CHUNK,
+} from '~/vue_shared/components/source_viewer/constants';
+import { splitIntoChunks } from '~/vue_shared/components/source_viewer/workers/highlight_utils';
+import LineHighlighter from '~/blob/line_highlighter';
+import languageLoader from '~/content_editor/services/highlight_js_language_loader';
+import Tracking from '~/tracking';
+import { TEXT_FILE_TYPE } from '../constants';
+
+/*
+ * This mixin is intended to be used as an interface between our highlight worker and Vue components
+ */
+export default {
+  mixins: [Tracking.mixin()],
+  inject: {
+    highlightWorker: { default: null },
+  },
+  data() {
+    return {
+      chunks: [],
+    };
+  },
+  methods: {
+    trackEvent(label, language) {
+      this.track(EVENT_ACTION, { label, property: language });
+    },
+    isUnsupportedLanguage(language) {
+      const supportedLanguages = Object.keys(languageLoader);
+      const isUnsupportedLanguage = !supportedLanguages.includes(language);
+
+      return LEGACY_FALLBACKS.includes(language) || isUnsupportedLanguage;
+    },
+    handleUnsupportedLanguage(language) {
+      this.trackEvent(EVENT_LABEL_FALLBACK, language);
+      this?.onError();
+    },
+    initHighlightWorker({ rawTextBlob, language, simpleViewer }) {
+      if (simpleViewer?.fileType !== TEXT_FILE_TYPE) return;
+
+      if (this.isUnsupportedLanguage(language)) {
+        this.handleUnsupportedLanguage(language);
+        return;
+      }
+
+      /*
+       * We want to start rendering content as soon as possible, but highlighting large amounts of
+       * content can take long, so we render the content in phases:
+       *
+       * 1. `splitIntoChunks` with the first 70 lines of raw text.
+       *     This ensures that we start rendering raw content in the DOM as soon as we can so that
+       *     the user can see content as fast as possible (improves perceived performance and LCP).
+       * 2. `instructWorker` to start highlighting the first 70 lines.
+       *     This ensures that we display highlighted** content to the user as fast as possible
+       *     (improves perceived performance and makes the first 70 lines look nice).
+       * 3. `instructWorker` to start highlighting all the content.
+       *     This is the longest task. It ensures that we highlight all content, since the first 70
+       *     lines are already rendered, this can happen in the background.
+       */
+
+      // Render the first 70 lines (raw text) ASAP, this improves perceived performance and LCP.
+      const firstSeventyLines = rawTextBlob.split(/\r?\n/).slice(0, LINES_PER_CHUNK).join('\n');
+
+      this.chunks = splitIntoChunks(language, firstSeventyLines);
+
+      this.highlightWorker.onmessage = this.handleWorkerMessage;
+
+      // Instruct the worker to highlight the first 70 lines ASAP, this improves perceived performance.
+      this.instructWorker(firstSeventyLines, language);
+
+      // Instruct the worker to start highlighting all lines in the background.
+      this.instructWorker(rawTextBlob, language);
+    },
+    handleWorkerMessage({ data }) {
+      this.chunks = data;
+      this.highlightHash(); // highlight the line if a line number hash is present in the URL
+    },
+    instructWorker(content, language) {
+      this.highlightWorker.postMessage({ content, language });
+    },
+    async highlightHash() {
+      const { hash } = this.$route;
+      if (!hash) return;
+
+      // Make the chunk containing the line number visible
+      const lineNumber = hash.substring(hash.indexOf('L') + 1).split('-')[0];
+      const chunkToHighlight = this.chunks.find(
+        (chunk) =>
+          chunk.startingFrom <= lineNumber && chunk.startingFrom + chunk.totalLines >= lineNumber,
+      );
+
+      if (chunkToHighlight) {
+        chunkToHighlight.isHighlighted = true;
+      }
+
+      // Line numbers in the DOM needs to update first based on changes made to `chunks`.
+      await nextTick();
+
+      const lineHighlighter = new LineHighlighter({ scrollBehavior: 'auto' });
+      lineHighlighter.highlightHash(hash);
+    },
+  },
+};