I attached a CPU snapshot taken while trying to type in a 20 lines file. There are lots of subclasses down the hierarchy for this one, if that makes any difference. Just tried 5380 and although the CPU gets maxed out as well, the editor keeps up with me while typing. In 5383, the moment I start typing the whole thing stops and I end up seeing what I typed about 10 seconds later. Let me know if I can provide more details.