According to some tests it does help. Since the page can only "start rendering" after it finishes calculating layout so a parallel layout algorithm lets you sta

According to some tests it does help. Since the page can only "start rendering" after it finishes calculating layout so a parallel layout algorithm lets you start showing the page sooner, which may feel snappier. This is even if the page ends up taking the same amount of time to render in the end (current browsers already try to parallelize some stuff).