>1. Does your machine use a spinning disk for its system drive, or SSD?
This really shouldn't be a question regarding the performance of a terminal window.
If cmd.exe starts fast regardless, then so should Powershell if it is going to replace it.
And on that note, on a new laptop with an SSD I can see a difference between Powershell and cmd.exe execution-to-prompt-ready time (however small that latency is).
As long as that's the case, Powershell simply isn't a viable replacement for cmd.exe