Speed of play was one of our biggest gripes. At high level one round could take an hour or more. High level play in 5E can be a bit of a grind if you have people that insist on rolling one die at a time, but you can get around that. If I could just get people to get over analysis paralysis I'd be all set.

I never did find a way to make 4E play much faster.
I have to say, I've never understood the desire to go back to 2e or B/X either. Play 5E with just PHB classes and subclasses, no feats. Maybe ignore backgrounds and skills. Wouldn't the result be close? That's probably a topic for a completely separate thread.
Monster lore was a bit of a mixed bag though, wasn't it? I remember one of my first games when I asked the DM to describe the monster we were fighting and he couldn't. All the MM had was stats - no description, no lore, nothing. I guess that worked if it was a monster from a previous edition that you recognized, but if not you were SOL. Monsters were just a bunch of stats and if you were lucky a picture.
That doesn't really seem to have anything to do with the edition though, more related to mod guidelines.