That's not true. Layout is still often slow (multi-hundred ms) on desktop. You can notice that.
Also powerful x86 CPUs are so good at shared-memory multithreading (cache coherency, large caches) that x86 is actually the best case for us (which is not to say we're bad on ARM, of course).
multi-hundred ms is slow....
But what is strange to me we have to go through a magnitude of handles and paralleling a browser engine to get to sub 100ms layout. Could we not further improve the current engine?
Also powerful x86 CPUs are so good at shared-memory multithreading (cache coherency, large caches) that x86 is actually the best case for us (which is not to say we're bad on ARM, of course).