🚀 Feature Request

Problem / motivation

When running Playwright Test with multiple workers, each worker has a noticeable “cold start” before it begins executing its first test job (process spawn + loading config/tests + worker-scoped fixture setup + first browser launch). In my environment this is ~3–6 seconds per worker, and it can feel even slower when launching from the CLI.

There are also small idle gaps during the run when a worker finishes and the next assignment requires initialization work before the next tests begin.

Proposed behavior (how it would work)

At start, Playwright spawns workers + warmWorkers worker processes.

Only workers are allowed to run tests concurrently (so CPU/parallelism is still controlled).

The extra warmWorkers sit idle after completing worker initialization (including worker-scoped fixtures / first browser launch if feasible).

When an active worker finishes its current assignment, the dispatcher can immediately schedule the next work item onto a warm worker (or promote a warm worker to active), so the next test work starts immediately, without a cold-start penalty.

The pool keeps warmWorkers “ready” in the background by replenishing spares as needed.

Example

What I’d like to see

Add an option to pre-warm additional “spare” workers so that scheduling can immediately pick up new jobs without waiting for worker initialization.

Proposed API

CLI

npx playwright test --workers=4 --warm-workers=4
# Concurrency stays at 4, but 4 extra workers are kept "hot" and ready.

Config

// playwright.config.ts
import { defineConfig } from '@playwright/test';

export default defineConfig({
  workers: 4,
  warmWorkers: 4, // new option
});

Motivation

Reduce tests execution time significantly when the number of tests is high.