This is really funny but I downloaded CCleaner (and I respect the company, in fact I use their Defraggler quite often), but other than cleaning some TEMP space, and losing my Firefox Tabs, CCleaner did NOT solve the problem. In fact, I tried it when the mouse was NOT sluggish, and the sluggishness of the mouse reappeared about 2 hours later! Can you believe that?
For now, the best solution for sluggish mouse remains the one recommended at annoyances-resolved.blogspot.com - that is, put the laptop to sleep and bring it right back. That takes just 2 minutes, but of course it is just a workaround.
If anyone has any additional ideas, let me know, Thanks!