This should not be ignored. Windows machines are a favorite for having lots of heavy anti-virus running on them. They can destroy I/O performance. Windows 10 has a "real time scanner" running by default, but many corporate-IT security teams will add more and more. This alone can seriously slow down windows vs linux.

> Anti-virus software makes process and file operations a lot slower.

It was a long time ago (~2006), and I honestly can't remember, but I feel like turning off anti-virus (and also backups, software updaters, and any other resident software) would have been one of the first things I would have checked. There was definitely something more fundamental going on.