If going by the stats that Xamarin gave[1] for Dalvik versus Mono on Android 4.0, Dalvik is also much slower than Mono. Though obviously Xamarin is not the most independent source in the findings, but I would believe it to outperform Dalvik in my own uses of both it and Dalvik for Android apps (I bought a license for it 6 months ago).
There's also some results by Koush Dutta[1] (Cyanogenmod contributer and Clockwork Recovery developer) from 2009 showing similar findings, though obviously that's way old and before Dalvik had JIT added in Android 2.2. We had a discussion sometime ago about that article on hn as well[3]
[1] http://blog.xamarin.com/android-in-c-sharp/
[2] http://www.koushikdutta.com/2009/01/dalvik-vs-mono.html
[3] https://news.ycombinator.com/item?id=421862