I have been trying to reproduce your problem. My toolbox icons are 40px apart, which is is the smallest Gimp allows (I'm using "medium" icons but "small" icons don't make the buttons smaller°) after hundreds of clicks zipping across the toolbox I can't reproduce your problem. Maybe my finger is faster than my wrist, or maybe my mouse is fast (I do reckon that you could have the problem with the slow mice of yore).
I don't think this a problem with Gimp itself. But Gimp is a demanding application and tends to exacerbate PC problems that are therefore first noticed with Gimp. I have several times remotely diagnosed mouse battery problems or keyboard troubles in this forum.
I don't think this a problem with Gimp itself. But Gimp is a demanding application and tends to exacerbate PC problems that are therefore first noticed with Gimp. I have several times remotely diagnosed mouse battery problems or keyboard troubles in this forum.