I have also tested this many times and I hardly see much of a difference. 10% sounds like a lot. What is the quality of your router and wifi, is it some cheap chinese junk? From what I can see there is less than 1% difference between wired and wifi.
MikroTik RB2011. I dont think that it looks like "cheap chinese junk". I was not looking where is problem. I had seen the difference and solved this problem with wired connection.