I upgraded by site from DNN v4.8.1 to 4.9.1 because I wanted the newer version of the text editor that works with Google Chrome. Since upgrading, my site has suffered very poor performance, most noticably on the forum module, sometimes taking up to 20 - 30 seconds to load a page.
Looking at other forum posts, the following seem relevant.
http://www.dotnetnuke.com/Community/Forums/tabid/795/forumid/118/threadid/278367/scope/posts/threadpage/7/Default.aspx
http://www.dotnetnuke.com/Community/Forums/tabid/795/forumid/65/threadid/278624/scope/posts/Default.aspx
http://support.dotnetnuke.com/issue/ViewIssue.aspx?id=9038&PROJID=2
Anyway, I'm suitably convinced that the caching problem with v4.9.1 is the cause of my problems, and since it's causing frustration right now, I'd rather not just wait until 4.9.2 is released (b.t.w. is there any way to know when 4.9.2 will come out?), so I'm wondering whether it is feasible to install 4.9.0 over 4.9.1 in the hope that it might give me a short term fix?
I do have a backup of when my site was on 4.8.1, but I'd rather not restore back to that, just because there has been significant activity on the forum since the upgrade that I'd prefer not to loose.