The SVN Compare with... action talks to the SVN repository to find previous revisions of a file. This can take several seconds per revision, adding up to much longer than it would take to type in the revision number. When comparing several files in a row against a specific revision, this can take seriously long time. If possible, make the popup such that one can enter a version while the revisions of the file in question are being fetched. If that is not feasible, add a menu item "Compare with specified revision" that just asks for the revision number, remembering it from last time. This would make it a lot faster to browse diffs.