System 7 Tune-Up 1.0 was released on January 13, 1992. It is not a complete system upgrade, but is a patch introduced by Apple for both System 7.0 and System 7.0.1 to handle low memory situations better.
If there isn't enough memory to run an application, Tune-Up was supposed to quit other applications not in use. It also switched to foreground printing automatically if there wasn't enough memory available for background printing.
Besides these features, the tune-up freed system resources from memory that weren't currently enabled -- notably AppleTalk. It also sped up network related activities, printing and, file copying.
Tune-Up also fixed known bugs with File Sharing and PrintMonitor corruption.