I find that emacs ruby-mode slows to a crawl when editing a 6000 line ruby file. Now I realize the file is way too long ( these things take time to fix / refac

I find that emacs ruby-mode slows to a crawl when editing a 6000 line ruby file. Now I realize the file is way too long ( these things take time to fix / refactor ), any tips on getting it to be more responsive?