I noticed this recently when I decided to watch Hitchcock's 'The Birds.'

It was almost absurd to me not only how bland and drawn out most scenes were, but how absolutely poorly acted it was. If it were not famous(ie didn't exist), and updated to today's vernacular and shot scene for scene, it would absolutely get reamed by critics.

Funny how much changes in just a generation or two.

Old movies are kind of slow but I'm much less frustrated because they are short: an hour, at most two. That's more than enough to tell a story. Modern movies are two hours at minimum with some crossing over three with absolutely nothing to tell (e.g Babylon 2022, completely pissed me off).

I don't think the reason is "public needed time to process info", more likely both the length and the intensity (of changing sights, not of meaning) were ultimately determined by production costs. Filming two hours is more expensive than one hour. Filling an hour with 60 one-minute cuts is more expensive then 30 two-minute cuts because of all the setup and decorations.

Production is now cheaper thanks to CGI, box offices are larger thanks to higher prices and the global market. You no longer have to be frugal when filming, the protection against sloppy overextended movies is now taste and not money. And taste is scarce.