The LR edit history of your images is stored in the catalog. This results in no extra memory being needed and has no limit on the number of steps stored. PS, on the other hand, stores the temporary edits in memory.
Outside of any possible memory problems LR might have generically, normally the only performance problems related to the number of edits is when there are a large number of "spot removal" steps.
Hi, thanks for the response.
I'm not talking about 'Edit History' ; I know how to manage it.
I'm in concern about the 'Activity History' ; LR maintain in-memory a history of all keyboard-type, metadata, change module, set/unset flags, add/delete to collection, move photo from folder-to-folder, , ... etc , which is available to 'undo' from the current state to the state when LR start the session.
This participate the LR's slowing down.
No, there is no feature in Lightroom to do that. Are you applying a lot of brush strokes with the adjustment brush?
in this case, I'm not in Develop, I'm in Library!
Make sort, metadata add, moves folder to folder, manage collections,...
and it comes slow.
Have you tried disabling the graphics processor in you Lightroom preferences? Doing this can often improve performance.