Should this bug also depend on 405745?
This is not a bug tracking any improvement to the awesomebar, it is just about work we plan for close future or consequences of improvements just landed in Nightly. That old bug is more general, I will look into its dependencies cause some could be no more valid.
I remember there is an old bug about pressing enter to go directly to the 1st result highlighted in the location bar history, like Chrome does and the addon Enter Selects.
that feature doesn't play very well with how we implement autofill and the action row. Enter Selects is still a viable option I think. It doesn't have lots of users though, so I don't think it's a critical functionality we need atm. We can re-evaluate in future.
I don't see any bugs for performance. It looks like the new awesombar produces results with <50% of the speed of the old one in general.