One of my fellow moderators, f4780y, has put together this sticky that explains about jailbreaking:
http://www.ipadforums.net/ipad-hacking/2838-jailbreak-explained-new-updated-2011-a.html
Plus, may I recommend you grab a snack and a beverage of your choice and head over the Hacking section of this forum. There are a whole bunch of stickies, tutorials and member's posts that talk about everything concerning jailbreaking.
And, to facilitate answers to your questions, I've taken the liberty of moving this post to the Hacking section so that the experienced jail breakers can chime in.
Oh, and from my personal view: Jailbreaking is perfectly safe and your iPad2 won't run slow (unless you put eleventy-million system tweaks on it ... that's gonna bog it down no matter what!). In fact, if you jail break it and don't install any tweaks, the only way you'll know its jail broken, performance-wise, is that you'll see the Cydia icon (the jail breakers "app store"). So, that's my view - YMMV.
Good luck in your decision and good luck.
Marilyn