This problem should only happen if your mouse is using a high polling rate, like over 125hz.
If you have fps issues while moving your mouse ingame try these steps.
1. Navigate to your Chronicles of Arcadia installation folder.
2. Rightclick on Client.exe
3. Click on the Compatibility tab
4. Click on the "change DPI settings" button (a new window should open)
5. Check the Checkbutton in the Programm-DPI section and select in the dropdownmenu "I login to windows"
6. Click OK in both windows
7. Restart your PC.
Let me know if it helped ♥