Recently, we made the jump from .NET 3.5 to .NET 4.0. Now we are seeing a huge performance hit in our web application. The w3wp.exe process is frequently spiking up to 70-80% and staying there for 10+ seconds. Previously, it would only spike up to around 50%, and only then for less than a second for pretty much any of our queries. This has made our app run at about 25% efficiency.
We were previously running .NET 3.5 (32 bit) IIS 6 Windows Server 2008 64bit
and are currently running .NET 4.0 (64 bit) IIS 6 Windows Server 2008 64 bit
Any guidance on how to solve this, or why it would run worse in .NET 4.0 would be much appreciated!