Well, I had heard it's a tiny bit faster to constantly jump while running, but it's impossible to tell. Would recommend that you DON'T jump too much to make it easier on medics trying to heal you, and to not block grenades.
Really jumping doesn't have many practical uses, but it helps sometimes to avoid one or two parts of damage from a crawler leap, back away from clots, mess with husks' aim, etc. I do it almost constantly because I've played ~1,000 hours of a game where you HAVE to navigate obstacles via jumping. Plus, it seems to keep my mind active if I'm constantly moving and looking around.