Reading some posts in the forums reminded me of some ideas about general performance fixes that have worked with D3 and POE.

Thanks to b0dega1991 post for reminding me of some old ARPG gaming tweaks to try.

You may want to try a some of these or all of these. You may need to try one setting and then launch the game to see if it helped. It sucks, but I tested several times after several game restarts.

{For those who are not comfortable changing computer settings remember you can always take pics of your settings on the computer screen with your cellphone before you make changes and access the pics later to change the settings back to what they were.}

TLDR: Mouse DPI polling may be causing FPS lag. Tweak Windows 10 mouse settings and your individual mouse manufacturer Windows apps to change DPI or "Enhanced pointer precision" settings in Windows 10

I am running Wolcen @ 4K UHD Full Screen Unwindowed on a system with an i7-6700, 16gb 2666 DDR4, 1080Ti with both CPU and GPU watercooled. I was experiencing dramatic FPS loss throughout the game at seemingly random times. But, most notable when in town in the central area with the waypoint and within the palace. FPS would be at solid 60 FPS while standing still and while moving it would fluctuate rapidly from 30-60 FPS. So, there are some general things I have applied in Windows after reading many posts for D3 and POE that I have tried in the past. It appears that it is common that Windows 10 has CPU throttling issues with high DPI polling mice (500hz-1000hz) and is usually a range that many First Person shooter players use with gaming mice. This is an ARPG so higher DPI polling might not matter.

As OP mentioned...mouse polling can be changed with many gaming performance mice within their respective mouse apps. But, I am using a Logitech MX wireless Trackball and is not catergorized as a "gaming" mouse. So, I tried a few things that you may want to try as well...

1) I went to the Windows 10 mouse settings and accessed the Mouse properties.

Windows search bar:

-Type: Mouse settings and click on settings
-Click "Related settings"(Right side of window)
-Click Additional mouse options
-In Mouse Properties click "Pointer Options" tab
-Under "Motion" uncheck "Enhanced pointer precision"
-Click Ok

Note--If you have a separate program that manages your specific mouse within Windows you may want to check that their isn't an enhance pointer precision option in there or you may want to adjust the DPI/pointer precision if you have a gaming performance mouse. If it is set to 1000hz or more may want to drop to like 250hz. Logitech, Razer, Corsair mouse settings apps, etc.

2) Tweak the Wolcen.exe launch parameters in Windows 10. The first setting to try is to "Disable fullscreen optimzations" and is something I picked up from POE forums to try within the POE game.

Locate your SteamLibrary folder and the Wolcen.exe

Example of my directory: E:\SteamLibrary\steamapps\common\Wolcen\win_x64

-Right click Wolcen.exe
-Click "Properties"
-Click "Compatibility" Tab
-Under "Settings" and check "Disable fullscreen optimizations"

Now click on "Change high DPI settings"
-Under "High DPI scaling behavior" check "Override high DPI scaling behavior." In the drop down window under need this make sure "Application" is selected.
-Click OK
-Click OK one more time.

Hope this may help some people. Not sure if the Wolcen team can look into possible optimizations for DPI polling solution for mice. May be the underlying issue as people have noted lag when moving the mouse around on the screen.