Last couple of days my mouse has been on a go slow. Scrolling is painfully slow with the wheel - normal documents (webpages, Word) are scrolling at 1 line per 'click' of the wheel. Adobe Reader is even slower, 1 small jump down for roughly every 20 wheel movements.
I've turned the scroll speed up to the max, no difference.
Thought back through what I'd changed recently, and remembered that I'd moved the receiver from the USB3 socket and put it in a USB2 socket (while booting linux from a USB 3 memory stick). Move the receiver back to USB3 and now everything's flying along like it should. Absolutely no idea why :'-D