"CPU-critical" does not necessarily mean that the program uses a high percentage of CPU time, it means that it will not run well on less capable CPUs for whatever reason, such as no threading or a single core. That probably means that it will in reality max out the time, but it doesn't say that. "CPU-demanding" is not a valid construction.
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enoon"CPU-critical"About the question. I don't know if you know these, but I'll say them. Perhaps you could find good words to describe them.