I've recently found the cause of my mouse lag (Logitech Desktop Wave), which usually works perfectly without any lag at all, except for when there is activity on my wireless network.
Clearly it is the wireless router interfering with the mouse. I logged into the router admin, and found it has the ability to switch the channel. There are actually 13 options.
I decided to try change, but if anything it made the lag worse.
Do I really have to try out all the channels by trial and error, or has anyone found a particular channel that works well with Desktop Wave?