Vitest 5: Prioritises Performance with a Shared Vite Server, Trace View, and Stricter Test Defaults

Vitest 5.0 focuses on speed, with reported gains of 8 to 25 percent in most setups and up to 53 percent in VM pools. It adds a vitest doctor command, Browser Mode Trace View, and vi.when. Defaults are stricter: clearMocks is true and unawaited async assertions fail. It requires Vite 6.4 and Node.js 22.12 or newer.