It depends on the site. It can be slow on ridiculously huge sites (ahem, TechCrunch, Gothamist, Macrumors, etc), but in that case you can just switch them to the Feed view instead of the Original view. The Feed view is instantaneous and it's how you get the speed back on those sites.
It's not ideal, but that means you can still use Original view for the 90% of sites that you still want to see. Plus you can set the Feed view as the default and just switch to the Original view on a per-site basis.
It's not ideal, but that means you can still use Original view for the 90% of sites that you still want to see. Plus you can set the Feed view as the default and just switch to the Original view on a per-site basis.