diff --git a/src/features/encoders/jxl/worker/jxlEncode.ts b/src/features/encoders/jxl/worker/jxlEncode.ts
index 40d71680..0378c2a7 100644
--- a/src/features/encoders/jxl/worker/jxlEncode.ts
+++ b/src/features/encoders/jxl/worker/jxlEncode.ts
@@ -14,17 +14,28 @@ import type { JXLModule } from 'codecs/jxl/enc/jxl_enc';
 import type { EncodeOptions } from '../shared/meta';
 
 import { initEmscriptenModule } from 'features/worker-utils';
-import { threads } from 'wasm-feature-detect';
+import { threads, simd } from 'wasm-feature-detect';
 
 import wasmUrl from 'url:codecs/jxl/enc/jxl_enc.wasm';
 
 import wasmUrlWithMT from 'url:codecs/jxl/enc/jxl_enc_mt.wasm';
 import workerUrl from 'omt:codecs/jxl/enc/jxl_enc_mt.worker.js';
 
+import wasmUrlWithMTAndSIMD from 'url:codecs/jxl/enc/jxl_enc_mt_simd.wasm';
+import workerUrlWithSIMD from 'omt:codecs/jxl/enc/jxl_enc_mt_simd.worker.js';
+
 let emscriptenModule: Promise<JXLModule>;
 
 async function init() {
   if (await threads()) {
+    if (await simd()) {
+      const jxlEncoder = await import('codecs/jxl/enc/jxl_enc_mt_simd');
+      return initEmscriptenModule(
+        jxlEncoder.default,
+        wasmUrlWithMTAndSIMD,
+        workerUrlWithSIMD,
+      );
+    }
     const jxlEncoder = await import('codecs/jxl/enc/jxl_enc_mt');
     return initEmscriptenModule(jxlEncoder.default, wasmUrlWithMT, workerUrl);
   }
diff --git a/src/features/encoders/webP/worker/webpEncode.ts b/src/features/encoders/webP/worker/webpEncode.ts
index 1b026dd9..035c166d 100644
--- a/src/features/encoders/webP/worker/webpEncode.ts
+++ b/src/features/encoders/webP/worker/webpEncode.ts
@@ -14,12 +14,18 @@ import type { WebPModule } from 'codecs/webp/enc/webp_enc';
 import type { EncodeOptions } from '../shared/meta';
 
 import { initEmscriptenModule } from 'features/worker-utils';
+import { simd } from 'wasm-feature-detect';
 
 import wasmUrl from 'url:codecs/webp/enc/webp_enc.wasm';
+import wasmUrlWithSIMD from 'url:codecs/webp/enc/webp_enc_simd.wasm';
 
 let emscriptenModule: Promise<WebPModule>;
 
 async function init() {
+  if (await simd()) {
+    const webpEncoder = await import('codecs/webp/enc/webp_enc_simd');
+    return initEmscriptenModule(webpEncoder.default, wasmUrlWithSIMD);
+  }
   const webpEncoder = await import('codecs/webp/enc/webp_enc');
   return initEmscriptenModule(webpEncoder.default, wasmUrl);
 }
diff --git a/src/features/encoders/wp2/worker/wp2Encode.ts b/src/features/encoders/wp2/worker/wp2Encode.ts
index f59478b1..1c12573b 100644
--- a/src/features/encoders/wp2/worker/wp2Encode.ts
+++ b/src/features/encoders/wp2/worker/wp2Encode.ts
@@ -14,17 +14,28 @@ import type { WP2Module } from 'codecs/wp2/enc/wp2_enc';
 import type { EncodeOptions } from '../shared/meta';
 
 import { initEmscriptenModule } from 'features/worker-utils';
-import { threads } from 'wasm-feature-detect';
+import { threads, simd } from 'wasm-feature-detect';
 
 import wasmUrl from 'url:codecs/wp2/enc/wp2_enc.wasm';
 
 import wasmUrlWithMT from 'url:codecs/wp2/enc/wp2_enc_mt.wasm';
 import workerUrl from 'omt:codecs/wp2/enc/wp2_enc_mt.worker.js';
 
+import wasmUrlWithMTAndSIMD from 'url:codecs/wp2/enc/wp2_enc_mt_simd.wasm';
+import workerUrlWithSIMD from 'omt:codecs/wp2/enc/wp2_enc_mt_simd.worker.js';
+
 let emscriptenModule: Promise<WP2Module>;
 
 async function init() {
   if (await threads()) {
+    if (await simd()) {
+      const wp2Encoder = await import('codecs/wp2/enc/wp2_enc_mt_simd');
+      return initEmscriptenModule(
+        wp2Encoder.default,
+        wasmUrlWithMTAndSIMD,
+        workerUrlWithSIMD,
+      );
+    }
     const wp2Encoder = await import('codecs/wp2/enc/wp2_enc_mt');
     return initEmscriptenModule(wp2Encoder.default, wasmUrlWithMT, workerUrl);
   }
diff --git a/src/sw/to-cache.ts b/src/sw/to-cache.ts
index dace22e2..cbc922f5 100644
--- a/src/sw/to-cache.ts
+++ b/src/sw/to-cache.ts
@@ -1,4 +1,4 @@
-import { threads } from 'wasm-feature-detect';
+import { threads, simd } from 'wasm-feature-detect';
 import webpDataUrl from 'data-url:./tiny.webp';
 import avifDataUrl from 'data-url:./tiny.avif';
 
@@ -75,6 +75,9 @@ import avifEncWasm from 'url:codecs/avif/enc/avif_enc.wasm';
 import * as avifEnc from 'entry-data:codecs/avif/enc/avif_enc.js';
 
 // JXL
+import * as jxlEncMtSimdWorker from 'entry-data:codecs/jxl/enc/jxl_enc_mt_simd.worker.js';
+import * as jxlEncMtSimd from 'entry-data:codecs/jxl/enc/jxl_enc_mt_simd';
+import jxlEncMtSimdWasm from 'url:codecs/jxl/enc/jxl_enc_mt_simd.wasm';
 import * as jxlEncMtWorker from 'entry-data:codecs/jxl/enc/jxl_enc_mt.worker.js';
 import * as jxlEncMt from 'entry-data:codecs/jxl/enc/jxl_enc_mt';
 import jxlEncMtWasm from 'url:codecs/jxl/enc/jxl_enc_mt.wasm';
@@ -86,10 +89,15 @@ import oxiMtWasm from 'url:codecs/oxipng/pkg-parallel/squoosh_oxipng_bg.wasm';
 import oxiWasm from 'url:codecs/oxipng/pkg/squoosh_oxipng_bg.wasm';
 
 // WebP
+import * as webpEncSimd from 'entry-data:codecs/webp/enc/webp_enc_simd';
+import webpEncSimdWasm from 'url:codecs/webp/enc/webp_enc_simd.wasm';
 import * as webpEnc from 'entry-data:codecs/webp/enc/webp_enc';
 import webpEncWasm from 'url:codecs/webp/enc/webp_enc.wasm';
 
 // WP2
+import * as wp2EncMtSimdWorker from 'entry-data:codecs/wp2/enc/wp2_enc_mt_simd.worker.js';
+import * as wp2EncMtSimd from 'entry-data:codecs/wp2/enc/wp2_enc_mt_simd';
+import wp2EncMtSimdWasm from 'url:codecs/wp2/enc/wp2_enc_mt_simd.wasm';
 import * as wp2EncMtWorker from 'entry-data:codecs/wp2/enc/wp2_enc_mt.worker.js';
 import * as wp2EncMt from 'entry-data:codecs/wp2/enc/wp2_enc_mt';
 import wp2EncMtWasm from 'url:codecs/wp2/enc/wp2_enc_mt.wasm';
@@ -97,8 +105,14 @@ import * as wp2Enc from 'entry-data:codecs/wp2/enc/wp2_enc';
 import wp2EncWasm from 'url:codecs/wp2/enc/wp2_enc.wasm';
 
 export const theRest = (async () => {
-  const [supportsThreads, supportsWebP, supportsAvif] = await Promise.all([
+  const [
+    supportsThreads,
+    supportsSimd,
+    supportsWebP,
+    supportsAvif,
+  ] = await Promise.all([
     threads(),
+    simd(),
     ...[webpDataUrl, avifDataUrl].map(async (dataUrl) => {
       if (!self.createImageBitmap) return false;
       const response = await fetch(dataUrl);
@@ -139,7 +153,15 @@ export const theRest = (async () => {
   }
 
   // JXL
-  if (supportsThreads) {
+  if (supportsThreads && supportsSimd) {
+    items.push(
+      jxlEncMtSimdWorker.main,
+      ...jxlEncMtSimdWorker.deps,
+      jxlEncMtSimd.main,
+      ...jxlEncMtSimd.deps,
+      jxlEncMtSimdWasm,
+    );
+  } else if (supportsThreads) {
     items.push(
       jxlEncMtWorker.main,
       ...jxlEncMtWorker.deps,
@@ -159,10 +181,22 @@ export const theRest = (async () => {
   }
 
   // WebP
-  items.push(webpEnc.main, ...webpEnc.deps, webpEncWasm);
+  if (supportsSimd) {
+    items.push(webpEncSimd.main, ...webpEncSimd.deps, webpEncSimdWasm);
+  } else {
+    items.push(webpEnc.main, ...webpEnc.deps, webpEncWasm);
+  }
 
   // WP2
-  if (supportsThreads) {
+  if (supportsThreads && supportsSimd) {
+    items.push(
+      wp2EncMtSimdWorker.main,
+      ...wp2EncMtSimdWorker.deps,
+      wp2EncMtSimd.main,
+      ...wp2EncMtSimd.deps,
+      wp2EncMtSimdWasm,
+    );
+  } else if (supportsThreads) {
     items.push(
       wp2EncMtWorker.main,
       ...wp2EncMtWorker.deps,