Screenpresso is fully optimized to be fast and keep memory usage low. Anyway, since this might not be enough for some people, Screenpresso uses another mechanism. After 2 minutes of inactivity, and when the last window of the software has been closed, Screenpresso also restarts itself automatically. This allows being absolutely sure the memory usage is always low, even if Screenpresso has been started weeks ago by the user.
If you still think Screenpresso uses too much memory, don’t be confused between private memory and shareable memory.