Ok, I've been using it all day, and over a period it seems to get slower (e.g. scrolling shows text in black and white until it gets a chance to colourise the text). I don't recall seeing anything like that until recent upgrades and I use it every day.
I've been measuring resident memory using top (at least, I think the %MEM column is the percentage of resident to total), and it only goes up. A restart had its memory at 14% which over time increased to 16%. A rebuild as suggested increased the total amount of memory from 16% to 19% and it's stayed there well after the rebuild is over. I'm assuming it should go up and down (my knowledge of linux memory usage is hazy), so I would have though this is a problem.
Closing all the editors hasn't reduced memory usage either. So it would seem to me that maybe there are some processes that are grabbing memory to do e.g. php indexing, but aren't releasing that memory at the end. Maybe these are the cause of the problem and the auto refresh just exacerbated that?
My machine is several years old with 2GB memory. However, the point is it didn't seem to be a problem until recently.
Anyway hope that helps.