Our problem started few weeks ago, there was no change on server side, so it just came from "nowhere".
We have Windows Web Server 2008 R2 with IIS 7 (7.5.7600.16385), this server is hosting 19 websites, 2 of them are Kentico CMS, both used to use very much CPU and memory use is growing all the time. Temporary solution was to configure memory limit in IIS, so when it goes over 4GB, w3wp process is restarted.
I need to know what is cause for that.
First thing I found out: both w3wp processes have many threads clr.dll!DestroyAssemblyConfigCookie+0x130ec, sometimes cycles delta for all those threads takes up to 2,000,000,000. It's about 2Ghz CPU.
Clr.dll is .NET library, but I couldn't find any documentation about modules inside. It's version .NET 4.0.30319.
Another thing is how can I check which library/thread is using most memory, where leakage can occure? Both websites are in production and visited all the time, so I'm not allowed to experiment or do any changes in code.