I changed the way we query for data and the way the page gets updated, so that we now basically never query for data without the user reloading the page. This is a pretty major change to the way the page updates, and I expect some bugs to show up somewhere.
This means scrolling on large comment threads or posts should now no longer lag, and comments should no longer resort when other people vote on things while you are looking at the comments (which quite annoyed some users). And in general the processing power the site requires should be massively reduced.
If you notice any bugs in the meantime, reloading the page should almost always fix it, and then send us a message so we can fix things properly.