CPU cores are still getting faster, but not at the 1980/90s cadence. We get away with that because the cores have been good enough for a decade - unless you are doing heavy data crunching, the cores will spend most of the time waiting for you to do something. I sometimes produce video and the only times I hear the fans turning on is when I am encoding content. And even then, as long as ffmpeg runs with `nice -n 19`, I continue working normally as if I had the computer all to myself.