JQuery Mobile on Android is definitely slow. (Tested A2 and A3Pre on Samsung Galaxy S, HTC Desire, ZTE Blade (edit: 2.2 Froyo) - with PhoneGap, stock browser, Opera Mobile)
Something has to be done. The experience is low quality.
Nevertheless JQuery Mobile is faster than JQ Touch (and a little faster than iUI). The transitions and UI elements are awfully slow. On all frameworks.
Will there be any significant speed improvements till the release? Or do we have to wait for quad core mobile phones?
@Chrisitan: a JS/Android Profiler would be nice