Computers have been “fast enough” for a very long time now. I recently retired a Mac not because it was too slow but because the OS is no longer getting security patches. While their CPUs haven’t gotten twice as fast for single-threaded code every couple years, cores have become more numerous and extracting performance requires writing code that distributes functionality well across increasingly larger core pools.
Mainframes are also like that - while a PDP-11 would be interrupted every time a user at a terminal pressed a key, IBM systems offloaded that to the terminals, that kept one or more screens in memory, and sent the data to another computer, a terminal controller, that would, then, and only then, disturb the all important mainframe with the mundane needs or its users.