Real web browsing performance is a unique combination of system performance, the Android browser itself, and what contributions or customizations (if any) the OEM has made in the shipping browser build. This is to say nothing of the numerous third party browsers out there. Qualcomm's Innovation Center recently made public a tool for gauging overall browser performance that it has used for a while to checkpoint and gauge performance in house and in collaboration with OEMs. We've used a subtest or two from it in a few reviews already, and it's named Vellamo.
Left to right: T-Mobile SGS2, Motorola Atrix, AT&T SGS2, HTC Sensation, LG Optimus 3D, Xiaomi Mi-One