If 4.02 is affected, then it's on your end. 4.0.2 has no important changes. If you're really concerned, try 3.5-2468 of the Dualcore Netplay branch before we changed the netplay input scheme.
Also, try using a Wiimote (even emulated) and compare. I'd be curious. I noticed that my mayflash has 2 frames worse delay than my Classic Controller via bluetooth, but I thought that was just Mayflash sucking ass.
Also, try using a Wiimote (even emulated) and compare. I'd be curious. I noticed that my mayflash has 2 frames worse delay than my Classic Controller via bluetooth, but I thought that was just Mayflash sucking ass.