Our system requirements are listed at:
In the past I’ve used very modest tablets (I prefer them), and I still use an Atom tablet (Toshiba Encore 2 Write 10) to control my machines. Most of the folks who are working with tablets set them up to only run the bare necessities (usually CM and DropBox) which seems to help with performance.
I find an active stylus helps with navigating dialog boxes at least, and a numeric keypad makes a useful pendant, see: