I benchmarked the Vita today, or rather its browser using BrowserMark and Sunspider. The results were quite underwhelming.
BrowserMark: Higher is better
PSVita: 15,652
iPhone 4S: 86,818
SunSpider Javascript: Lower is better
PSVita: 42,748ms
iPhone 4S: 2,255ms
For comparison purposes, it's slower than the iPhone 3GS according to some of Anand's old benches. I'm going to chalk this up to poor coding in the Vita's laughably bad browser. There's no way it's that slow.
I know the Vita isn't a MID, but I wonder why Sony insists on putting such horrible browsers on its gaming systems.