Hrm, how long are the freezes?
Does the save progress bar appear?
Are there any errors in the output after saving?
Is it all objects?
Does this happen for all projects or just this one?
Does it ever crash? If so, could we see the crash report? It’s likely something visual.
May I know your specs?
Lastly after the barrage of questions, a thread to look over that has some possibilties: