I know I've spent half a day messing around before and then smashed out a piece of work in a few hours and still had the impression of being productive. Simply because the majority of employees aren't as productive as me. Being a very productive and capable developer will open lots of opportunities but some of us don't want to climb the ladder. I just want a comfortable job and be good at it.
I'd never take a pay cut though. If you kept the same productivity at a lower pay then you're effectively saying they overpaid you before. 20% less pay is 20% less work in my eyes.