I have 25,800 images linked to my catalog.
My catalog is 508 MB
Or ~20K of DB size per image. Maybe that's not so bad.
I've seen folks indicate they have over 75K images in their catalog, do they also have a 1.5 GB catalog?
I optimize with every backup. Have loaded into SQLite and VACUUMed it and there was no space recovered - suspect this means the LR Optimize is doing a good job.
LR performs well, but backing up to my NAS drive, with gigabit ethernet, takes a while. I tend to let it do its thing and walk away, but sometimes - end of the night - I want to shut down the PC and have to wait for this very slow backup to finish...
What is your Image Count/Catalog Size?