Hello
Sorry if this sounds obvious, but it's not so much "better/worse", rather it's "easier/harder".
Slower swings are easier (for me) to hit the ball well, usually with the trade off of less distance.
Good advice is to try and match the swing speed of your irons with that of your woods. In theory it should give a consistent swing/timing.
Having said all that, I've been playing bloody awful lately, so what do I know......
Have fun