wsh-server-tuning

name	wsh-server-tuning
description	Server-side optimizations for WSH 2026 — compression (gzip/brotli), cache headers, static asset caching, artificial delay removal, and Express tuning.

WSH: Server Tuning

Server-side optimizations reduce transfer sizes and improve response times. Compression alone can reduce text-based assets by 60-80%.

Use this skill when optimizing Express server configuration, cache headers, compression, or removing artificial delays.

Techniques

1. Enable Compression

import compression from "compression";
app.use(compression());

Or for better compression, use shrink-ray-current which supports Brotli:

import shrinkRay from "shrink-ray-current";
app.use(shrinkRay());

Impact: FCP -20-40%, LCP -10-20%, SI -20%

2. Fix Cache Headers

// Before (in app.ts)
res.header({
  "Cache-Control": "max-age=0, no-transform",
  Connection: "close",
});

// After — remove the global middleware entirely
// Then set proper caching per route type:

// Static assets with hash in filename (immutable)
app.use("/scripts", express.static(path.join(...), {
  maxAge: "1y",
  immutable: true,
}));

// Images and media (long cache)
app.use("/images", express.static(path.join(...), {
  maxAge: "1y",
}));

// API responses (no cache or short cache)
// Don't set cache headers on API routes

Impact: Repeat-visit performance dramatically improved

3. Enable etag and lastModified

// Before (in static.ts)
serveStatic(path, { etag: false, lastModified: false })

// After
serveStatic(path, { etag: true, lastModified: true, maxAge: "1y" })

4. Remove Connection: close

The Connection: close header forces new TCP connections for each request, preventing HTTP keep-alive.

5. Remove Crok AI Artificial Delays

// Before
await sleep(3000);  // TTFT delay
await sleep(10);    // Per-character delay

// After
// Remove both sleep calls, stream response immediately

Impact: User flow score for Crok AI chat improved significantly

Pitfalls

Pitfall	Symptom	Fix
Compression on already-compressed files (images, videos)	Wasted CPU, no size reduction	Exclude binary types or let the library handle it
Cache-Control on API responses	Stale data	Only cache static assets, not API
Cache-Control on HTML	Users see stale app	Set no-cache for HTML, long cache for hashed assets

VRT Risks

Change	Visual Impact	Mitigation
Compression	None	Safe, Low risk
Cache headers	None	Safe, Low risk
Delay removal	None visually, timing changes	Safe for VRT

Project-Specific Notes

• Global cache-disabling middleware in application/server/src/app.ts
• Static routes in application/server/src/routes/static.ts with etag/lastModified disabled
• Crok AI delay in application/server/src/routes/api/crok.ts
• Connection: close header forces no keep-alive
• Webpack output filenames don't use content hashes currently ([name].js not [name].[contenthash].js)
  • Consider adding content hash to enable immutable caching