Skill Lag
It may not be the case at all, but the fact you could play normal on one system and not the other makes me think the slower system could have been running a scan or a windows update or something like that in the background using more CPU resources. the next time you have that issue, shrink the game, hit ctrl-alt-del and bring up the task manager. You may find the culprit running in the background causing your problem. The fact that is was skills only is odd though.
Maybe something to consider. GL