If you care about performance I wouldnt recommend building the application in PhoneGap or Titanium or anything similar.
From personal experience:
PhoneGap is very easy to use/learn and can build good looking UIs very fast. The problem is that is really slow compared to other solutions. You basically build with HTML.
Titanium would result in a faster - more responsive application BUT it would require more coding and tuning. Here you basically build with java script. Also, despite the fact that is universal there might be cases where you would have to build separate code for android and for iOS for example to do the same job.
For best user experience I would recommend (and I think many will agree) going native for each platform and trying to keep a consistent UI.
Also since this is not the first question about the mentioned frameworks please have a look here and on many other questions that compare these frameworks.