With regard to the Marx Brothers, it's interesting to see how live performance played a factor in the pacing of their respective movies. Coconuts and Animal Crackers were lifted directly from their stage shows, and both have a much slower and stagier pace than their other movies (especially the other Paramount films). Their performances seem to be timed to accommodate the the audience reaction they got used to dealing with night after night. Monkey Business through Duck Soup, which were never performed live, were the Marx's most rapid-fire movies - lightening-quick performances and direction, nobody giving a damn if the audience was keeping up with the gags they were throwing out like candy at a parade. Since they never performed that material live, and never had to tweak their timing to accommodate the viewers, it's as though they felt free to perform at the pace they felt comfortable with without being fettered by the audience.
Then came the MGM years, when Thalburg convinced the boys go on the road to test run the material slated for filming. Not surprisingly, the resulting films are peppered with "audience reaction" pauses (Groucho trying to bring the contract info focus, Groucho ordering food from the porter, Chico selling Groucho racing tips, etc.), and everything slows down a bit as a result.
Kind of interesting to see how performers key into a certain pace based on learned audience reaction even when the audience isn't there.