Undo becomes very slow

Version 2.6.1 (1213)
macOS 10.13.6

I’ve seen this issue come up before but I’m getting it again now, not sure why, and wonder how I can mitigate this

Can you send me a screen recording? And does it get better when you restart Glyphs. And is it different when you disable plugins (hold Opt+Shift) when you start Glyphs.