Could you pls explore browser benchmarks being single threaded? I mean, when I use Chrome or Firefox on Android isn't the browsing experience implemented as multi-threaded (e.g. when I have the 8-core S5)?
There are multiple threads, but the benchmarks are specifically looking at JavaScript performance (as it's the only thing they can actually measure - anything claiming to measure drawing performance is a lie, whether or not they realize it, but I digress), and JavaScript is all single-threaded.
There is going to be painting and such while the benchmark runs, which will use a second thread, but that's about it. And that's going to be relatively light compared to actual usage where you're scrolling around and such.
The majority of the other threads of a browser are I/O bound (networking, disk, etc...) and won't be using much of the CPU.