The image rotation has now been replaced by a zoom in. It was at 10% before but I brought it down to 7% because I think it looks better (also, it's seven). One problem is that the images, particularly the smallest ones, look blurry after the zoom. That can be overcome by making Wordpress generate the 107% images and then displaying them at the smaller size by default, but implementing it will involve lots of fiddly changes, so I haven't done it yet.
The slider is gone, replaced with a static (except for the zoom) image, because it was too resource-heavy. Firefox uses a lot less CPU when resizing now.
I also played around with the menu bar a bit. The search function was being hidden at widths below 1210px before, which I didn't agree with, so I stopped that from happening. That created its own problem of the search icon overlapping the menu, so I fixed that too. The problem that I'm yet to fix is the menu spilling down to a second row at certain sizes, but I'll do that when I next have a moment to work on the site, which could be later tonight, but right now I'm popping out.