checked the follow distance on slave1 and it was definitely trailing the follow on slave2

not only did it appear this way from all screens, slave1 was also getting stuck on a lot more corners/doorways etc compared to slave 2.

I've switched from:
master & slave1 on PC1
slave2 on PC2

to:
slave1 & slave2 on PC1
master on PC2

just using octopus to broadcast keystrokes, no autohotkey and it seems to have resolved matters
(at least until I get into some ugly situation with dead master and wanting to control both slaves hmmmmmm)