I met VS IDE TOO SLOW issue for some time. Loading solution and F5 to debug took so long time! Finally I figured out the reason: I put my project source code and 3rd parties onto C: while my VS is living and started on E:. The key point here is that C and E are two different disks NOT just two partitions!
The solution is pretty easy: moving all source code and 3rd parties onto the same disk as VS lives..