I recall that when the Pi2 was released, the build of Raspbian was not optimized for multi core.
Did this ever change? I would like to give a try again to Raspbian (I am using retropie on my pi2 for the moment, but I do no desktop work at all); but only if it has been optimized. I recall that web surfing last year was quite slow, and youtube was also laggy, until the cache was filled.
Most likely these are issues due to the low memory on board, but having a multi core OS would also help.