Possible workaround / cause of the recent FPS issues

I'm assuming the techies at Riot will know in greater detail just what those changes entail, but apparently the recent Windows 10 update broke something with game displays. Two things that might work are changing your resolution and / or changing your display scaling.

I always run Windows 10 at 150% scaling, because my resolution is 2560 x 1440. Switching to 100% and then back to 150% genuinely fixed the issue for me (although I don't know if it will persist after a shutdown). To be clear, let me write up what I did, in bug report style. :P

1. Launch a game. For the purposes of testing, I made a custom game. I did not include bots or any other players.
2. FPS are dramatically reduced compared to normal levels. From upwards of 144Hz to below 60fps for most of the game. The issue gets worse when moving the camera ( 20 fps and lower ).
3. The following did not make a difference:

• Restoring default graphics settings.
• Lowering graphics settings.
• Changing resolution.
• Changing window mode.

Expected outcome: FPS remain around the 144fps mark throughout. Actual outcome: FPS remain around the 50fps mark, and frequently below the 20fps mark.

Possible workaround:

1. Launch a game. For the purposes of testing, I made a custom game. I did not include bots or any other players.
2. Alt+Tab to switch from the game to the desktop.
3. Right click the Windows 10 Start menu icon, and click on Settings.
4. Click on System and, using the dropdown menu under "Change the size of text, apps and other items", switch to 100% scaling.
5. Alt+Tab to the game. FPS have returned to normal levels.
6. Alt+Tab to System settings, and switch back to 150% scaling.
7. Alt+Tab back to the game. FPS improvement persists.

I would have recorded before and after, but I honestly didn't expect it to work. Sorry! :P