I had someone report MORE lagging with this OS version than the last. However, it turned out to be a theme issue. So, if you're having any issues with this latest OS, make sure you're not using any 3rd party themes. You'll need to remove them (not just activate another theme.)
I've noticed a big improvement in streaming (youtube) with both 167 and 168. The only other difference is more free memory with 168. I actually found 167 to memory leak way more than 168. I would say 168 doesn't leak much if any at all.