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From: oster@dewey.soe.berkeley.edu.UUCP
Newsgroups: comp.emacs
Subject: CPU Efficiency emacs wins over vi
Message-ID: <19219@ucbvax.BERKELEY.EDU>
Date: Tue, 2-Jun-87 19:05:10 EDT
Article-I.D.: ucbvax.19219
Posted: Tue Jun  2 19:05:10 1987
Date-Received: Thu, 4-Jun-87 07:31:08 EDT
Sender: usenet@ucbvax.BERKELEY.EDU
Reply-To: oster@dewey.soe.berkeley.edu.UUCP (David Phillip Oster)
Organization: School of Education, UC-Berkeley
Lines: 21

There is a common case where emacs uses much fewer cycles than vi.
When you page through a file by hitting the page key on your keyboard
quickly, vi insists on processing your input one key at a time,
laborously drawing page after page that any intelligent program could
tell you aren't interested in. Emacs is an intelligent program: if
your type ahead would cause the current re-display to be invalid, it
doesn't bother finishing the re-display, it uses its CPU time slot to
DO what you want instead of to SHOW what you don't want, and when it
is done DOING, it shows just the final state, not all the intermediate
state. Richard calls this "Load Shedding" as the cpu gets more and
more loaded, Emacs uses less and less cpu time (because it does less
drawing). By comparison vi wastes huge amounts of CPU time, and my
time drawing stuff I'm no longer interested in.

If you read Richard Stallman's paper on the philosphy of Emacs
(published in the proceedings of the ACM conference on Text Processing
in Portland Oregon in the early '80s, you'd already know this stuff.)

--- David Phillip Oster            -- "The goal of Computer Science is to
Arpa: oster@dewey.soe.berkeley.edu -- build something that will last at
Uucp: ucbvax!dewey.soe!oster       -- least until we've finished building it."