I had a lag in my mouse movement on my 2nd PC. I am using a Razer gaming mouse, so I tried to lower the DPI and polling rate, and it wasn't helping much.
Then, I found that if I quit the Razer Synapse app on my 2nd PC, the lag is gone. And I can set my polling rate to 1,000 and DPI at 1,600 still no lag.
Hope this helps other with similar situation as me.