I don't think it's specifically poor performance, but places that have attracted more optimisation attention. An operating system is a big old chunk of work, an

I don't think it's specifically poor performance, but places that have attracted more optimisation attention. An operating system is a big old chunk of work, and not every element can be honed to a fine edge. It's good that OS developers do actually respond and focus on areas users have flagged up as well, builds better systems.