Earlier quoted context omitted.
On debian the program is cpulimit.
I think using nice or renice is better practice. Hard throttling is way more inefficient.
The bizarre part, when it comes to Flash, is that I've yet to see an actual difference in the application behavior when I throttle down it's CPU usage. I would think that if it normally maxes out 7 of my 8 logical cores, being limited to 40% of one core would make introduce slowness. But I guess that's just an indication of how poorly written the OS X flash client it.