trickle for cpu ?

[Zenaan Harkness <zen@freedbms.net>]

I know of nice, but that just changes process priority, but still
allows a process to use up to 100% of cpu.

trickle is a bandwidth shaper for network usage and is easy to use and
works well.

Is there an equivalent for CPU, so that I can "shape" the "cpu
bandwidth" of an application?

I want to be able to say "use maximum 10% of CPU".

In the past, I wanted to do the same for memory and disk IO, to
restrain firefox. My relatively modern pc with 8G RAM no longer
motivates me in this way, but I would definitely like to throttle CPU.

TIA
Zenaan