Anand
Fastest GM

Bogolyubov was pretty fat.
hi
Thanks for that relevant, insightful, and very very useful comment. I'll take that to heart. I should dissect this response and analyze it for motifs.
No one goes around timing these guys with a stopwatch. Why would they? As a general rule, very talented young GMs move very quickly. The young Vishy Anand was famous for winning games with more than an hour left on his clock, while his opponent was in time trouble.
But do any chess reporters mention, besides the match outcome and moves, the time left over by each player?

What you mention about Grischuk is indeed interesting. Moves really fast on speed chess and really slow on slow chess 😊

Hooper and Whyld wrote that in his later years Friedrich Sämisch was almost always under time pressure and that "he lost more games on time than any other master and in one tournament, Linköping 1969, he lost all 13 games this way. In serious play he could not bring himself to make a decision without examining every possibility."
But in his early days, Sämisch was not only a fast player, but one of the most successful blindfold players, scoring 84.7% out of 300 such exhibition games, usually at 10 board simuls, but his record was 20 boarsd.. Eliot Hearst mentions that Alekhine was impressed with his "technically perfect, fast and confident play".
Sämisch won a game against Capablanca in 1929 Karlsbad in which Capablanca famously blundered a piece in the opening.
In classical time control, who among the GMs present or past make moves the fastest?