When clicking on Import from the Administration functional area, the resultant Import process page should load in 1-2 seconds. It's taking much longer. Once the page is open, if a site filter is chosen, it again takes a long time for the page to re-load (15 sec to 1:30).
Download and install the latest patch which contains all fixes from previous patches. If you are running an older version, download and install the latest version and then the patch.