That's extremely strange, because I do not have problems with speed. Perhaps it is something else interfering, a bad driver, or poor support for your paticular system?

Typically things open near instantly for me. But, keep in mind in a VM, things is just horrible slow. Probably even more so if you run Windows 10 from a Linux host OS – I have had a lot of problems with that, and eventually I just gave up, because it was not fast enough for me.

For Windows, it is much, much better to setup dual boot.