Some 2 or 3 weeks ago I started having this problem. The Windows loading screen, which did not take 5 seconds before, now takes several minutes. Once logged in to OS, everything works fine.
PS ... Scrap Windows and use Linux.
What Linux distro do you use?
I'm using Linux Mint which is a derivative of Ubuntu.I can't see how the operating system affects browsing unless you prefer Internet Explorer to Firefox or Opera or Chrome....R
I'm curious, do you still run antivirus/firewall on Linux?
Mint looks quite nice actually, I'm guessing there's a USB bootable version.
If you just want a version of Linux that runs from a USB stick have a look at Puppy Linux. It's forte is older PCs.
What about for high end PC's?