Basically the performance depends on the components you have on the page and the features enabled for them. Therefore in order to advice you how to improve the performance in your case we need to check the problematic page declaration along with the AjaxRequest.
Do you want to have your say when we set our development plans?
Do you want to know when a feature you care about is added or when a bug fixed?
Telerik Feedback Portal
and vote to affect the priority of the items