Does jailbreaking your iPhone always mess it up?

I've jailbroken my iPhone, and i've installed ONE tweak. This is the only thing i plan on installing, and i don't plan on ever opening cydia again. Jailbreaking my old iPod has reduced it to taking 30 seconds just to open up settings, so i don't want this to happen to me relatively new iPhone 5.So anyways, If i only have that one thing downloaded will my phone get messed up at all?

I had an iPhone 4 until just a few months ago and it was jailbroken the whole time. You will notice it runs a little slower but that's because you have additional things using memeory.

Actually, jailbreaking will not mess up the device but if you are careless and may have installed an incompatible software. So to avoid messing up with jailbreaking your phone make sure to:

1. Read the package description
2. Follow the guide conscientiously.
3. You must know how to jailbreak.