tests run 3x slower than Jest

Describe the bug

Tests run 3x slower than Jest for me.

Reproduction

vitest: https://github.com/sachinraja/zod-to-ts/tree/vitest jest: https://github.com/sachinraja/zod-to-ts/tree/main

System Info

System:
    OS: Linux 5.15 Pop!_OS 21.10
    CPU: (8) x64 Intel(R) Core(TM) i7-10510U CPU @ 1.80GHz
    Memory: 5.03 GB / 15.44 GB
    Container: Yes
    Shell: 5.8 - /usr/bin/zsh
  Binaries:
    Node: 16.11.1 - ~/.asdf/installs/nodejs/16.11.1/bin/node
    Yarn: 1.22.15 - ~/.asdf/installs/nodejs/16.11.1/.npm/bin/yarn
    npm: 8.0.0 - ~/.asdf/plugins/nodejs/shims/npm
  Browsers:
    Brave Browser: 96.1.33.106
    Firefox: 95.0
  npmPackages:
    vite: 2.7.4 => 2.7.4 
    vitest: 0.0.100 => 0.0.100

Used Package Manager

pnpm

Validations

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[Demivan]

@sachinraja Tests are taking ~800ms now. And with threads disabled ~650ms.

[Demivan]

I saw that threads are slower too. Alter checking it with nodejs profiler I can see that workers are idling a lot. Will investigate where bottleneck is.