Visual Studio Build Very Slow

Question

This applies to both 2008 and 2010 versions (and probably earlier ones too). Also to both C++ and C# projects.

An initial build (after reboot) runs at normal speed

Answer 1

am using VS2015 on Windows 10 and had the same issue. I cleared the %temp% and prefetch directories that didn't work.Then I changed the power saving settings from Balanced to High performance and it worked.