https://bugs.winehq.org/show_bug.cgi?id=43049
David K. hevanen@googlemail.com changed:
What |Removed |Added ---------------------------------------------------------------------------- Resolution|--- |FIXED Status|UNCONFIRMED |RESOLVED
--- Comment #4 from David K. hevanen@googlemail.com --- This has been fixed at some point. It seemed to be caused by certain spell effects which permanently reduced the frame rate until using Alt+Tab.
However, a test with patch 8.12 and Wine 3.10-staging got me a relatively stable 150 fps without any major frame drops. As of patch 8.13, LoL has an anti-cheat protection that does not work with Wine, so it would be hard to test it now in any case.