Hi Rahul - Hard to tell (or to recreate) what the problem is from your desciption. Is it possible for you submit a bug report through support, with a little more detailed description? That's usually the best way to get some attention on these sorts of issues.
We are currently investigating some performance issues for a client, and it seems like the issues only appears once one or more A/B tests are running on the site.
When we set up A/B tests we get a lot of the following exceptions in the log files:
This is happning even though we are using EPI server 11.
In sum this leads me to believe that there are some performance challenges with the EPiServer A/B testing module.
Has anyone else seen this?