Will jailbreaking my iphone 5s make it slow?

I'm just going to get jellylock 7 that's all. I'm scare that my phone will break or stop working

No not neccessarily it really has to do with the components of your phone. The Ipod touch 2G is only a little laggy when jailbroken so I can't see the Iphone 5 running slow when jailbroken. So I would go for it.

Or you'll have to pay the ridiculous fine if you get caught and are in the USA