Last week, Just Cause 3 saw a much needed performance patch across PC and consoles. The patch brought the game to version 1.02, bringing improved loading times, fixed various issues, added new features and optimized online stats.
Avalanche Studios have released a followup update, Patch 1.021, on the PC to bring further improvements – specifically tailored to PC issues.
The 99MB patch will improve stability when exiting to your desktop and improve memory management. This means that the game shouldn't crash anymore when you exit to the desktop and should perform better through improved memory management.
The developers are currently working on more improvements for the game, so if this patch doesn't fix your problem, report it and hold tight, a fix will come eventually.