These are important for many reasons. Without these techniques, we can't even do line rate GigE on "common place" servers, let alone have any CPU left over to do more then just send packets.
Actually, my testing shows a falure to utilize even 100baseTX fully. Even in a switched FDX environment (no collisions) I can't achieve line rate without bumping the packet size up. Considering that the smallest box is a quad-CPU SMP machine (550Mhz), I don't think that there is a CPU shortage <grin>.
The your problem probably lies elsewhere. A decent operating system (e.g. FreeBSD) can do line rate on 100baseTX with something along the line of a Pentium-166. Not exactly a very powerful machine by current standards. (And btw this was measured three years ago...) Steinar Haug, Nethelp consulting, sthaug@nethelp.no