diff --git a/packages/frontend/src/components/MkImageEffectorDialog.vue b/packages/frontend/src/components/MkImageEffectorDialog.vue
index de2c92bbd6..5605baff51 100644
--- a/packages/frontend/src/components/MkImageEffectorDialog.vue
+++ b/packages/frontend/src/components/MkImageEffectorDialog.vue
@@ -20,6 +20,7 @@ SPDX-License-Identifier: AGPL-3.0-only
 		<div :class="$style.container">
 			<div :class="$style.preview">
 				<canvas ref="canvasEl" :class="$style.previewCanvas"></canvas>
+				<MkLoading v-if="canvasLoading" :class="$style.previewSpinner"/>
 				<div :class="$style.previewContainer">
 					<div class="_acrylic" :class="$style.previewTitle">{{ i18n.ts.preview }}</div>
 					<div class="_acrylic" :class="$style.previewControls">
@@ -74,6 +75,8 @@ const emit = defineEmits<{
 
 const dialog = useTemplateRef('dialog');
 
+const canvasLoading = ref(false);
+
 async function cancel() {
 	if (layers.length > 0) {
 		const { canceled } = await os.confirm({
@@ -91,7 +94,9 @@ const layers = reactive<ImageEffectorLayer[]>([]);
 
 watch(layers, async () => {
 	if (renderer != null) {
-		renderer.setLayers(layers);
+		canvasLoading.value = true;
+		await renderer.setLayers(layers);
+		canvasLoading.value = false;
 	}
 }, { deep: true });
 
diff --git a/packages/frontend/src/components/MkWatermarkEditorDialog.vue b/packages/frontend/src/components/MkWatermarkEditorDialog.vue
index db231f90d7..46d952ce90 100644
--- a/packages/frontend/src/components/MkWatermarkEditorDialog.vue
+++ b/packages/frontend/src/components/MkWatermarkEditorDialog.vue
@@ -20,6 +20,7 @@ SPDX-License-Identifier: AGPL-3.0-only
 		<div :class="$style.container">
 			<div :class="$style.preview">
 				<canvas ref="canvasEl" :class="$style.previewCanvas"></canvas>
+				<MkLoading v-if="canvasLoading" :class="$style.previewSpinner"/>
 				<div :class="$style.previewContainer">
 					<div class="_acrylic" :class="$style.previewTitle">{{ i18n.ts.preview }}</div>
 					<div v-if="props.image == null" class="_acrylic" :class="$style.previewControls">
@@ -89,6 +90,8 @@ import { genId } from '@/utility/id.js';
 
 const $i = ensureSignin();
 
+const canvasLoading = ref(true);
+
 function createTextLayer(): WatermarkPreset['layers'][number] {
 	return {
 		id: genId(),
@@ -232,6 +235,13 @@ let imageBitmap: ImageBitmap | null = null;
 async function initRenderer() {
 	if (canvasEl.value == null) return;
 
+	canvasLoading.value = true;
+
+	await Promise.all([
+		sampleImage_3_2_loading,
+		sampleImage_2_3_loading,
+	]);
+
 	if (sampleImageType.value === '3_2') {
 		renderer = new WatermarkRenderer({
 			canvas: canvasEl.value,
@@ -270,7 +280,9 @@ async function initRenderer() {
 
 	await renderer!.setLayers(preset.layers);
 
-	renderer!.render();
+	await renderer!.render();
+
+	canvasLoading.value = false;
 }
 
 onMounted(async () => {
diff --git a/packages/frontend/src/utility/image-effector/ImageEffector.ts b/packages/frontend/src/utility/image-effector/ImageEffector.ts
index 282f36778f..63f5d6fa4b 100644
--- a/packages/frontend/src/utility/image-effector/ImageEffector.ts
+++ b/packages/frontend/src/utility/image-effector/ImageEffector.ts
@@ -196,40 +196,35 @@ export class ImageEffector<IEX extends ReadonlyArray<ImageEffectorFx<any, any, a
 		return shaderProgram;
 	}
 
+	private async getOrLoadShaderProgram(fx: ImageEffectorFx): Promise<WebGLProgram> {
+		let shaderProgram = this.shaderCache.get(fx.id);
+		if (shaderProgram) return shaderProgram;
+
+		let shaderSource: string;
+		if (typeof fx.shader === 'string') {
+			shaderSource = fx.shader;
+		} else {
+			shaderSource = await fx.shader();
+		}
+		shaderProgram = this.initShaderProgram(`#version 300 es
+			in vec2 position;
+			out vec2 in_uv;
+
+			void main() {
+				in_uv = (position + 1.0) / 2.0;
+				gl_Position = vec4(position, 0.0, 1.0);
+			}
+		`, shaderSource);
+		this.shaderCache.set(fx.id, shaderProgram);
+		return shaderProgram;
+	}
+
 	private async renderLayer(layer: ImageEffectorLayer, preTexture: WebGLTexture) {
 		const gl = this.gl;
-
 		const fx = this.fxs.find(fx => fx.id === layer.fxId);
 		if (fx == null) return;
 
-		const cachedShader = this.shaderCache.get(fx.id);
-		let shaderProgram: WebGLProgram;
-
-		if (cachedShader != null) {
-			shaderProgram = cachedShader;
-		} else {
-			let shaderSource: string;
-
-			if (typeof fx.shader === 'string') {
-				shaderSource = fx.shader;
-			} else {
-				shaderSource = await fx.shader();
-			}
-
-			shaderProgram = this.initShaderProgram(`#version 300 es
-				in vec2 position;
-				out vec2 in_uv;
-
-				void main() {
-					in_uv = (position + 1.0) / 2.0;
-					gl_Position = vec4(position, 0.0, 1.0);
-				}
-			`, shaderSource);
-		}
-
-		if (cachedShader == null) {
-			this.shaderCache.set(fx.id, shaderProgram);
-		}
+		const shaderProgram = await this.getOrLoadShaderProgram(fx);
 
 		gl.useProgram(shaderProgram);
 
@@ -268,6 +263,13 @@ export class ImageEffector<IEX extends ReadonlyArray<ImageEffectorFx<any, any, a
 	public async render() {
 		const gl = this.gl;
 
+		// 全レイヤーのshaderロードを事前に完了させる
+		await Promise.all(this.layers.map(async (layer) => {
+			const fx = this.fxs.find(fx => fx.id === layer.fxId);
+			if (!fx) return;
+			await this.getOrLoadShaderProgram(fx);
+		}));
+
 		{
 			gl.activeTexture(gl.TEXTURE0);
 			gl.bindTexture(gl.TEXTURE_2D, this.originalImageTexture);
@@ -359,7 +361,7 @@ export class ImageEffector<IEX extends ReadonlyArray<ImageEffectorFx<any, any, a
 			this.paramTextures.delete(k);
 		}
 
-		this.render();
+		await this.render();
 	}
 
 	public changeResolution(width: number, height: number) {