After using a emacs for a while all I see is
Garbage collecting...done in the modeline. At this point emacs is constantly garbage collecting but can't free any memory and has to be restarted. Emacs is sluggish in general on this machine, even after a fresh restart, as it's constantly garbage collecting so something is clearly wrong.
I've tried all builds I could think of for emacs. I've installed 24.5 and 25.1 from brew. I've tried the binaries same binaries from emacsforosx.com. Right now I'm running the version at https://github.com/railwaycat/mirror-emacs-mac, as a last try.
Everyone I've talked to is happily using emacs on a mac so it's clearly nothing wrong with emacs itself. How can I find out which package / function is causing this nightmare?
I'm on a brand new macbook pro running the latest version of el capitan.