Comment by Someone

We’re not talking about what humans call “a moment”. For a (modern) computer, a millisecond is “a moment”, possibly even “a long moment”. It can run millions of instructions in such a time frame.

A modern CPU also has multiple cores not all of which may be needed, and will be supported by hardware that can do lots of tasks.

For example, sending out an audio signal isn’t typically done by the main CPU. It tells some hardware to send a buffer of data at some frequency, then prepares the next buffer, and can then sleep or do other stuff until it has to send the new buffer.