Blender Global undo is very slow on complex scenes When I'm working with complex scenes (a few million polygons with +- some subdivision), say you're making a weapon highpoly model, the Blender's Global Undo becomes extremely slow. 

Even with simple changes in the object mode, moving something and undoing, applying a modifier and undoing it or anything like that Blender freezes for 5 - 10 seconds and then responds again. 

This is making working on such scenes really difficult. And it isn't my specs, I've got an i7 6700, 24 gigs of memory etc.

Are there any options, maybe addons or something to help avoid this issue? 

Thanks! :)
The undo buffer works by actually saving the entire blend file in memory, and loading it to undo. If you have such big, complex files, that'll take a while.

A possible way to speed things up would be to enable Simplify (scene properties panel) to restrict the subdivision level, and to write parts of the scene to different blend files and link them into the scene (rather than having all data in one blend file).