I'm using Illustrator CC 25.0.01 on a MacBook Pro (Catalina v 10.15.4). I'm working from my desktop and not on a server because I'm having so many issues. When saving files with pattern swatches (even if the files are only 30MB), it often takes 30 min or so to do background save. But more often than not, it seems, after waiting for the doc to save (and watching the progress in the tab), I get an error message that Illustrator can't save due to errors. If I'm feeling patient, I will save again. When I save this second time, Illustrator doesn't do a background save; the status bar comes up and I wait. For files this small, I have waited HOURS - literally - since I didn't want to lose work - and about 75% of the time, the file will save. But why it takes so long, I don't understand? And during this time, if I right click on the AI icon on my dock, it will tell me Illustrator is not responding.
When this happens, these files then give me yet ANOTHER error when I try to open them: 'Illustrator could only partially read this file. We recovered as much of the file as possible, but some content might be missing. Open to view the recovered file.'
It's becoming incredibly counter-productive. I spend hours waiting for things to save. I uninstalled and reinstalled Illustrator. This was happening with the older version so I updated to the newer version and it's still happening.
30mb is not a small file, mine are often 2.5mb going to press as final art. This suggests that you are not familiar with turning off pdf compatible setting by doing a save as. Are you using a pattern fil which is more efficient, or objects stepped & repeated multiple times.
If you need more help, let us know how your art is constructed.