I have the same problem too and I'm thinking it might be because of my cheap bluetooth dongle. Using 1 wiimote is fine, but 2 at the same time brings delayed input
Oh, a friend found a really annoying problem. On some not-too-early version of Dolphin (71xx) is all amazing right, this seems to happens only on 73xx versions.
Problem: The up and down swing command (that make mario spins in air or hold an object or character) is assigned to L-R Triggers. L swing down, and R swings up. In 71xx, no problem, just with one single touch in "up-down-up-down", mario spins in the air, precisely. But with 73xx, i need to do this between 10~50 times to mario make something. No matter how fast, how precisely or how "specific-time-alternated" i press the buttons, notthing happens until i repeat it for some 30 times. Its like that version did not recognize that im pressing the buttons. o_O
Yes, the emulator is systematically configured.