So I run the game in borderless windowed mode, and usually it runs fine and all is well. However, ever since patch 5.5, borderless windowed mode is arbitrarily capping my frame rate to 55fps. I have a dual monitor setup, both monitors are the same exact model (Asus PG278QR.) Both are set to the same refresh rate of 165hz in windows settings and in nvdia control panel settings, so it's not the issue of the window being limited by desktop refresh rates. No other game has this issue. I do not have any frame limits in-game, in the nvdia control panel, or in any other 3rd party tuners. I have double and triple checked that. Yes my GPU can handle high refresh rates with no issues. (1080ti)
Running the game in full screen does not have the frame rate cap. Disabling my second monitor using windows key + p, booting the game, then re-enabling it with the game already running prevents the cap from happening on launch, and borderless windowed mode runs normally. Once the second monitor is enabled again though, the refresh rate on it seems terrible unless I focus the monitor, game frame rate seems fine though. I don't want to have to disconnect and reconnect my 2nd monitor every time I run this game, It's extremely annoying.
Yes my graphics drivers have been updated with full clean installs using DDU. Yes I've fully clean-reinstalled the game itself as well.
I will mention I have had this issue once before, but it randomly went away one day so I stopping trying to troubleshoot it. This happened after patch 5.4 dropped, so similar scenario.
Another bizarre thing to note about this issue is that the frame rate is only capped while the game is focused. You heard me correctly, as in, the frame rate tanks when the game is in the foreground, but when I tab out to move to my other monitor, the frame rate skyrockets into the 300s. As soon as I click on the game again, it caps itself back down to 55. In my google searches I have come across others sharing this issue with this game in the past so I know it's not just me, but unfortunately found no solution other than running the game full screen which isn't an option for me. The common denominator seems to be borderless windowed mode combined with a second monitor.