Hello bhavin patel,
We deeply apologize for the late reply.
If you want to add new tab from a button cliek event then we would recommend you to use code behind for the purpose you want to achieve.
Can you please explain in more details what did you mean by "Performance issue"?
Can you please send us some sample code or explain in more details what are you trying to achieve, we need to know this information in order to be able to help you?
All the best,
the Telerik team