Instruct: Classify a review as either positive or negative.
Query: Inconsistent

I have had this mouse for 8 months now. At first, I was quite pleased with its light weight and ergonomic profile, and I found its performance satisfactory. However, over time I have found that there are some days when it is very sluggish in its response. I have tried changing this surface and also repositioning with respect to the wireless receiver; however, nothing has seemed to help.A mouse is useless if it doesn't respond consistently. I am looking for a new one.