my laptop has a processor speed well below a requirement for a game but plays it flawlessly, what are risks?

As long as your comp is kept cool enough, there are no risks.

EDIT: Your laptop will most likely underclock (speed down) itself before it gets too hot. In severe cases it'll shut-down without warning to prevent the CPU from getting any hotter.

You also want to be aware if the hard drive is spinning like crazy all the time your playing. Also a sign you need more RAM.