I create an empty file. Then I type "well, ", I copy that and then start pasting it by keeping Ctrl-V down. When I have about 4 lines of wells I'm already noticing that every new instance appears slower and slower. The top utility shows lyx is using 100% CPU for this task. After a few more lines the speed is down to about 2 wells/second. When the wells are all pasted, cpu usage returns to < 1%.
I don't use copy/paste much but there's another problem. Now say I want to add some math after the wells. I press Ctrl-M and start typing some equation. The characters seem to appear at the same speed as the wells did, at about 2 characters/second. In other words, it is pretty much unusable. Lyx is using 100% CPU for this, too. Then I add 20 new section headers, each saying "Hello". I add enough so that the entire screen only consists of hello headers. Now everything is fast again, until I add a few lines of text or scroll so that the previous text is visible. Typing in non-math text works fine, or at least the lag is much less. Using the "-graphicssystem raster" option doesn't help. The problem wasn't always there. I'm actually pretty sure that this very same version of LyX I'm using now has worked fine before and it's some other update which is causing the problems. However, since I don't see similar problems with other applications, it still seems like some kind of Lyx-problem, too. Any ideas? I'm using LyX 2.1.3 on an up-to-date Archlinux. I have similar problems with two machines, a netbook and a desktop. They have different graphics cards (intel and nvidia). The other computer is also using an older kernel (3.19.3 iirc), so that's probably not the problem.
