There is nothing very special about the cache creation process, it just uses quite a lot of processing power. Actually, not even very much (compared to e.g. some benchmarking program), it basically just goes through all the system's hard drives and analyzes the found files.
New processors are smart in a way they can shut down the internal parts of the processor that are not in use. This is why a new processor can run smoothly without much usage, but overheat when computer is under heavy usage.
I have a Pentium 4 (Prescott) on my work computer and it also heats up a lot under heavy usage. The fan is also heat controlled, so under heavy usage the fan noise is very high as well.
There is no such thing as using a cpu beyond its limits, if a processor can't handle all the usage a software can generate there is a problem with the hardware (mainly in the cooling).
You could test your processor's cooling by running some very cpu intensive program, such as http://www.softpedia.com/get/System/Benchmarks/CPUMark.shtml to see whether the processor also overheats with it.
Or, you could consider purchasing a better cooling system to it.
