Do you mean that the performance issue is in the administration, or in the public part?
We are in the process of writing an article on optimizing the overall performance of Sitefinity, both for the administration and the public part. We will try to finish the article in the beginning of next week. Once we are ready, we will follow up a reply to this thread. Meanwhile, if you provide some more information about your project, we will give our best to provide you guidance on optimizing.
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