the fraction of DNA devoted to regulation, such as promoter sequences, is a tiny fraction of that devoted to coding

Given that most of DNA is junk, considering "information" in raw storage terms makes little sense. It may be a tiny fraction, but is it an important contributor to genetic fitness? If it is, then it's hard to argue that evolution has slowed down.

I see no reason to think that. You can often kill an organism by changing 1 bit in its genome.

ETA: I'm not disputing that, but see above. I'm trying to qualify the information's overall contribution to genetic fitness.