I just tried again and open and closed Hexxmap and the laggy mouse issue seems to be fixed! Not sure what triggered it but if it happens again I will let you know!
OS: Arch Linux x86_64
Kernel: Linux 6.18.51-1-lts
CPU: 12th Gen Intel(R) Core(TM) i7-12700KF (16+4) @ 5.00 GHz
GPU: AMD Radeon RX 580 Series [Discrete]
Memory: 15.10 GiB / 31.15 GiB (48%)