The memory consumption of GC languages with GC turned will never decrease, and basically keep increasing unless completely idle. Efficiency has nothing to do with it. conses are generated whether you want it or not, for every single line of Lisp executed.
Not everything in emacs is written in elisp. I can tell you _for sure_ that turning off GC in emacs doesn't result in a runaway train of resident memory.
sure, but if you're not generating enough garbage over the lifetime of the app for it to matter, why waste time collecting? especially is your collector is an old-school design that hangs the app for a user-noticeable amount of time...
