Is that even true tho? I'm pretty sure it slows things down, thats what most people say anyway.Recent Win10 versions indeed compress the Windows directory to save space.
Don't worry about it, compression doesn't have any adverse effects on anything. It's not going to slow your computer down, in fact it probably speeds things up since less data needs to be read (that's been my experience anyway).
If you want, you can look at the attributes of each folder and uncheck the compression box, but it's gonna take a while and again you don't need it.
It doesn't, at least not if you have a CPU made in this century.I'm pretty sure it slows things down, thats what most people say anyway.