Robert Borgala the author of the great .emu emulators has this to say about the sound lag and offers hope:
the audio code on Android requests an safe buffer size from the OS and because of this, the latency may vary depending on the device. Being a multi-tasking phone/tablet/PMP, all the audio runs through a sound server (mixing, volume adjustment, filters) before being sent to the audio hardware which also adds some inherent latency. There are a few things I can try in future updates to try and minimize the latency: allow the user to override the buffer size to a lower value in case the device is able to handle it properly, and re-write the entire audio back-end to use OpenSL instead of the Java audio API, in case the device's sound driver is better optimized for it. Future Android OS updates may also improve the sound server performance though it's up to Google on whether they'll actually work on it. Overall I'd say the Android sound server gives reasonably good performance, not as good as iOS but the server they use has been refined for years in MacOS. It's certainly much better than something like WebOS (version 1.x, haven't tested anything newer yet) which is easily up to 3 times worse than Android and makes any kind musical instrument app very unreliable.
Willgoo has sent him a ydpg18a to help with the sound lag fix
Update: This is also an example of why this is happening.
the stock android soundserver is audioslinger and it has an high latency, about 170ms.... pulseaudio was ported to android months ago and registered a latency of about 20ms... i don't understand why rom developer don't include pulseaudio, witch is open source, on android.