Just had to RMA my X20 mouse.  EVGA sent me a BNIB X20 as a replacement.  Plugged in the new one, using the new USB dongle as the wireless receiver, and the new USB cable as the charging cable.  My mouse lags constantly while plugged in.  It works perfect fine when on wireless.  But when it dies or gets low and I have to charge it, I plug it in and it goes crazy.  My last mouse did not have this problem.  I RMA'd it because something broke on it internally.  
  
Video of the issue - https://www.youtube.com/watch?v=oVatjcpFIvg 
 
I use Unleash, Firmware is updated, tried old wireless receiver, tried old cable, same problem.  Tried Different USB ports.  Tried USB port on the keyboard, tried USB port on the monitor.  I also plugged the USB cable into a wall outlet, it charges, and the mouse is connected to PC via 2.4 GHz, and it does not lag.  It is only when the mouse is hardwired to the PC that it lags.

I have the same issue, did you find a way to resolve this ??

This is the first time I am hearing this. 
 
Do you happen to have another computer that you could try this mouse on to see if the same behavior continues?
 
Please email us at Support@EVGA.com so we can help you to find a resolution.
 
 

EVGATech_ChrisB
This is the first time I am hearing this. 
 
Do you happen to have another computer that you could try this mouse on to see if the same behavior continues?
 
Please email us at Support@EVGA.com so we can help you to find a resolution.

Well, this post is from a year ago.  What I found out is this specific mouse did not like being plugged into my monitor or keyboard's passthrough USB ports.  The original mouse before it did not have that issue, I have always used my passthrough USB ports.  Seeing as you guys force people to pay for RMA shipping even though there is an issue with your product, I opted to just buy a new X20 on Amazon since it was on sale for like $18 and I would get it the same day; versus paying $10 to ship something back to you and get it back in 2 weeks.  The new mouse, worked just fine, confirming the issue is with the mouse itself.  However, few months later with the new mouse, the mouse wheel broke.  Again, not paying to ship my RMA.  So bought another X20 on Amazon for less than $20.. 3 months later, the mouse wheel broke again..  
  
Bottom line is with support and product quality going down hill I just gave up and bought from another brand.  Real Shame because I loved the ergonomics of the X20.  I wish EVGA was still what it was a year or two ago.