The Atom helper can consume more than 100% cpu on Mac OSX. My old macbook pro (early 2011) becomes unbearable slow, but I like Atom, especially for producing my blog posts.
To get a manageable load on the cpu, I finally found two ways to make it work: remove all hidden .git<(span)> directories and always starting Atom from the commandline and in safe mode:
$ atom –safe<(span)>