If you use ASIO drivers they bypass most of the Windows kernel and stream directly to the 'hardware' interface. If you have a decent audio interface, the latency wouldn't be noticeably worse just 'because its Windows'. Most latency measurements I've seen (and I've seen my share) don't show any real difference between MacOS and Windows (using ASIO drivers) when using the same audio device. On Macbooks (ime) the graphical redraw performance is significantly worse than on Windows machines. Meaning more general CPU load and increased spikes in CPU usage when lots of redrawing is occurring (for example when lots of audio meters are firing on channel strips), which can cause audio glitching as a consequence. So generally I associate poorer performance with Macbooks, all else being equal. Everything about the Macbook hardware is much better quality than the equivalent hardware from manufacturers who are bundling Windows with their laptops, though. Apart from the lack of any upgradeability on the recent MB models, that kinda sucks.