[nigrosimone]

app.handle() calls Object.setPrototypeOf on req and res for every request. On Node 24 and 26 this still costs about 2.4 us per request, -22% of app.handle() for a res.send('Hello World!') (in-process bench, numbers per Node version in expressjs/perf-wg#15).

Fix: app.listen() passes to http.createServer an IncomingMessage and ServerResponse with app.request and app.response as prototype, and app.handle() skips the switch when the prototype is already the right one. Mounted apps still switch and restore as before. Apps that call http.createServer(app) themselves keep the switch.

Test: app.listen() serves a request with no switch (fails without the fix with 2 switches), and a mounted app still sees its own prototypes.