That's a slightly different problem. There's no thing as saturation for a performance benchmark like SPEC; we can always conceive of a faster processor (even if we don't know how to build one). Saturation is the problem that once you are at (or near) 100% pass rate on a test of pass/fail questions, there's no room for the score to keep going up and the test has lost any power to discriminate between competing options.
However, both kinds of tests are susceptible to over-fitting: an LLM can be trained on the exact test questions, and a CPU can be designed with eg. branch predictors and cache sizes tuned specifically to handle a particular benchmark or workload.
