I have noticed that the undo system are sometimes very slow. Undo of one or two steps back is OK but if I want to go back 10-20 steps it is faster to manually go through the history files. It is if the project files is large, some megabytes, that this problem starts.
The current undo system is great but it is not perfect. DEX allows and I know that some users like to store files within the project file increasing the file size even more. And also some 3D parts occupies much space. Maybe a solution would be to split up the project file in the history. It would complicate things but maybe it is needed. Like one file for static items (3D symbols, files) and one for the rest.
It would open up for extremely smaller backups as the static file do not have to be copied every time and undo could be much faster. But you can't just grab an old file and use it. You must open a history file through DEX so DEX can integrate the static file with the other.
Disk usage will of course also be much smaller which is very good.