I get input lag in Windows around 100-150 dwarves. It feels like the GUI not registering clicks, but since the GUI is a separate thread on top of DF it's possible that events are simply lost if a step of the simulation takes a long time. E.g. the selection box will keep running underneath the autosave window or complex world events (migrants, beasts, caravans, season changes), and I think I'd rather have that then random buffered events all playing at once, but certainly GUI integration could be improved a bit.

Using Proton I have mouse input lags when the time is running. So, I pause the game to draw complex things. I hope the Linux version will be reased soon. And I hope they hire somebody to implement multithreading.

I'm getting occasional (maybe every 3 squares?) dropped input in the free-hand mode and sometimes the box draw mode gets "stuck" in the same spot.

I'm getting some input lag on Linux, via Proton, but I just pause the game and it gets snappy again. That's been working for me so far.