Emulating a processor's (limited) resources, including clock speed

I would like a software environment in which I can test the speed of my software on hardware with specific resources. For example, how fast does this program run on an 800MHz x86 with 24 Mb of RAM, when my host hardware is a 3GHz quad core amd64 with 12GB of RAM? Emulators such as qemu make a great point of running "almost as fast" as the underlying hardware; I would like to make it run slower. Is there a way to do that?