[Bug 43049] New: League of Legends: massive performance regression

https://bugs.winehq.org/show_bug.cgi?id=43049

Bug ID: 43049
           Summary: League of Legends: massive performance regression
           Product: Wine
           Version: 2.6
          Hardware: x86-64
                OS: Linux
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: directx-d3dx9
          Assignee: [e-mail]
          Reporter: [e-mail]
      Distribution: ---

League of Legends ran at about 80-150 fps with wine-staging 2.4, with 2.6 and
2.7 it runs at ~20 fps and since 2.8 the game is just a slideshow (4-5 fps,
though the in-game fps counter still claims 15-20 fps). These figures are with
CSMT enabled.

It is worth noting that the first few seconds of the game run at decent frame
rates and more importantly, that alt+tabbing out of the game and back
temporarily boosts the frame rate back to 80 fps. It then quickly falls back to
5-20 fps over the next ~5 seconds. This makes it seem like some resources are
not being properly released or something similar.

I also tested with vanilla wine 2.8 and the behavior is very similar, so it's
not a staging-only problem.

The graphics card is a RX 470 with the RadeonSI driver.