The
most speed increasing thing in the new editor (I am sure) is
the grid. Even more in combination with "times 8" tilesets. (L2, L3 as examples)
But often I encounter cases where I want to turn off the grid for 1 or a few things and after that turn it right on again.
A hotkey for ON/OFF toggling of the grid would be a great acceleration for level creation speed.
I might even argue about moving the grid option from "Settings" menu to the "Global" tab so that it is instantly avialable at all time, as I change the grid quite frequently (2,4,8,16 being the most common settings).
Yes, thinking more about it:
A dedicated Hotkey + having the grid setting in the "Globals" tab would both be very beneficial. Even if it isn't a level variable.