A good editor is worth their weight in gold. Myself, I’m a frugal person, so I do my own ferocious self editing. I once belonged to a writers group, and the material the members submitted for critique made me cringe. Their story ideas were good, but were full of unnecessary adjectives, numerous misspelled words, run on sentences, and they had their characters grunting, snorting, huffing and puffing. I would spend time editing and when I gave back the material, the people were offended. I figured these people were looking for praise and not the truth.
It’s always sensible to follow due diligence in submitting your first draft of your book to an editor by making as fool-proof a copy as possible for you because first, it is your own creation, and secondly, a horrid draft sent your editor can end up frustrating both you and him or her. Make your own corrections to the extent you can, so that will make the job of your editor that much lighter and the end result would be a lot more effective.