If you are experiencing excessive Wi-Fi latency, here are some things you can try:
Use the QB Conductor Protocol instead of Apple’s Network MIDI. Conductor’s protocol gives the Wi-Fi connection the best opportunity for low-latency performance in a noisy environment.
Use a dedicated Wireless Router. Having other people watch streaming video using the same radio channel can only make things worse.
Use a wired network connection for your computer. If both your computer and your iPad are using Wi-Fi to connect to a Wi-Fi router, then your input must travel over Wi-Fi twice – once from the iPad to the router, and then again from the router to the computer. This will double your latency — the time taken to send a message over the wired connection is miniscule compared to what it takes to send it over radio.
Try an “ad-hoc” wi-fi network that doesn’t use a wi-fi router at all. In this mode your iPad is transmitting directly to the wi-fi card in your computer. Personally I find these “ad-hoc” connections a little too fiddly — wiring your computer to the wi-fi router should be virtually as fast, despite involving more equipment.
Upgrade to a 802.11N Wireless Router. 802.11N provides a lot more bandwidth than the earlier wireless standards, and as a side effect delivers much lower latency. It also operates at higher frequency ranges, which may have less interference at your location.
Disable 80211.b/g compatibility mode in the router. 802.11N routers often support the older 802.11 standards (a, b, g); supporting the old standards prevents the 802.11N from running as fast as it should, as the router has to periodically switch modes to check for older devices.
Disable “Automatic Channel Mode”. Some Routers have a mode that automatically looks for channels with less interference and will automatically change. While this sounds like a good idea, you will get a spike in latency when it does change its mind about which channel it wants to use. Experiment with different channels
Eliminate sources of interference. Malfunctioning equipment can generate a lot of RF noise. I recently had an LCD Monitor that was causing digital-TV interference, but only figured this out when the monitor finally died, as that was when the annoying interference was gone.
Try moving the Router to different places; closer to where the iPad is is better, a clear line of sight will help; going through walls and appliances can only make things harder for the radio link