All the data movement shouldn't even be a blip on your CPU usage. I think I get about 0% to 0.7% CPU usage on cgminer on a low-end Celeron.

If you're getting high CPU usage then something is wrong. Make sure "gen=0" is in the helixcoin.conf file.  If you're on Linux make sure it's using the libOpenCL from the fglrx install and not the broken one from the AMD APP SDK (this might apply to Windows also, I have no idea). The broken SDK libopencl causes an irq storm.