perf(build): faster builds via JSON compression skip + zopfli/gen2 tuning

.circleci/config.yml

@@ -78,7 +78,10 @@ jobs:
       NODE_OPTIONS: --max-old-space-size=12288
     executor:
       name: default
-    resource_class: xlarge
+    # gen2 is ~1.4x faster CPU at +20% credits/min. Only this job runs the
+    # CPU-bound `yarn build`, so it's the one place the trade pays off (per
+    # Voltaire's gen2 rollout). Fall back to xlarge if gen2 is unavailable.
+    resource_class: xlarge.gen2
     steps:
       - checkout
       - attach_workspace:

bin/assert-compressed.sh

@@ -1,13 +1,13 @@
 #!/bin/bash
 
 #
-# A utility script to assert that all CSS, JS, JSON, and SVG files have corresponding .gz compressed versions
+# A utility script to assert that all CSS, JS, and SVG files have corresponding .gz compressed versions
 #
 # Usage: assert-compressed.sh
 #
 
 # Find all files that should be compressed
-FILES=$(find public -type f \( -name "*.css" -o -name "*.js" -o -name "*.json" -o -name "*.svg" \))
+FILES=$(find public -type f \( -name "*.css" -o -name "*.js" -o -name "*.svg" \))
 ORIGINAL_COUNT=$(echo "$FILES" | wc -l)
 
 # Check each file for a corresponding .gz version

data/onPostBuild/compressAssets.js

@@ -23,7 +23,12 @@ const piscina_1 = __importDefault(require("piscina"));
  */
 const onPostBuild = async ({ reporter }) => {
     const cwd = path_1.default.join(process.cwd(), 'public');
-    const globResult = await (0, fast_glob_1.default)('**/*.{css,js,json,svg}', { cwd });
+    // JSON (mostly Gatsby's page-data.json) is excluded: nginx is configured with
+    // `gzip on; gzip_types application/json; gzip_static on;` so JSON is
+    // live-gzipped on the way out. Pre-compressing it with zopfli was the bulk of
+    // onPostBuild time for ~5-10% extra ratio over nginx's live gzip-6. Following
+    // Voltaire, which dropped JSON pre-compression for the same reason.
+    const globResult = await (0, fast_glob_1.default)('**/*.{css,js,svg}', { cwd });
     const files = globResult.map((file) => {
         return {
             from: path_1.default.join(cwd, file),

data/onPostBuild/compressAssets.ts

@@ -20,7 +20,12 @@ import Piscina from 'piscina';
 
 export const onPostBuild: GatsbyNode['onPostBuild'] = async ({ reporter }) => {
   const cwd = path.join(process.cwd(), 'public');
-  const globResult = await fastGlob('**/*.{css,js,json,svg}', { cwd });
+  // JSON (mostly Gatsby's page-data.json) is excluded: nginx is configured with
+  // `gzip on; gzip_types application/json; gzip_static on;` so JSON is
+  // live-gzipped on the way out. Pre-compressing it with zopfli was the bulk of
+  // onPostBuild time for ~5-10% extra ratio over nginx's live gzip-6. Following
+  // Voltaire, which dropped JSON pre-compression for the same reason.
+  const globResult = await fastGlob('**/*.{css,js,svg}', { cwd });
 
   const files = globResult.map((file) => {
     return {

data/onPostBuild/compressAssetsWorker.js

@@ -2,7 +2,10 @@ const fs = require('fs/promises');
 const { gzipAsync } = require('@gfx/zopfli');
 
 const options = {
-  numiterations: parseInt(process.env.ASSET_COMPRESSION_ITERATIONS || '15', 10),
+  // Default 1: zopfli's deflate ratio plateaus after the first iteration
+  // (<0.5% byte savings vs. 5/15 for 25-45% more time per file). Set
+  // ASSET_COMPRESSION_ITERATIONS higher for production if max ratio is wanted.
+  numiterations: parseInt(process.env.ASSET_COMPRESSION_ITERATIONS || '1', 10),
 };
 
 const compress = async ({ from, to }) => {