ASP.NET application on "IIS 8.5" on "Windows Server 2012 R2" performs poorly compared with "IIS 7.5" on a "Windows Server 2008 R2"

Solution 1:

I believe this has been covered in several places, but the Balanced power plan can cause excessive transitions between performance states. This results in exceptionally poor performance, and affects both physicals and virtuals.

Change the power plan to High Performance to use the hardware to its limits.

Slow Performance on Windows Server 2008 R2 when using the “Balanced” Power Plan:

https://support.microsoft.com/en-us/kb/2207548

https://sqlserverperformance.wordpress.com/2010/09/28/windows-power-plans-and-cpu-performance/

http://www.brentozar.com/archive/2010/10/sql-server-on-powersaving-cpus-not-so-fast/

EDIT by @oliver:

Switching to the High Performance power plan resulted in these PerfMon stats: