Here's some interesting data about how long Vulkan takes to initialize.
WSL:
VkInstance: 42 ms
VkDevice: 13 ms (llvmpipe)
Dell XPS laptop:
VkInstance: 61 ms
VkDevice: 2.9 ms (Intel Xe), 9 ms (llvmpipe)
Some Asus laptop:
VkInstance: 1.84 s (!)
VkDevice: 38 ms (Nvidia), 5 ms (Radeon), 26 ms (llvmpipe)
Well, there is no point in parallelizing this.