I've using MIDI for a very long time (30 years or so). MIDI was introduced as a Music Communication Protocol with very low overhead.
MIDI captures and communicates musical instructions in just a few bytes of data. This is a fraction of the space Digital Audio would use.
By using only instructions MIDI was able to run on the old slow CPUs and smaller memory without latency for the most part.
I am now running newer much faster CPUs and a whole lot more memory and all I have for most part is a running gun battle with latency.
I now have to use USB 3.0 for my MIDI connections where I used 5 pin DIN serial before.
USB 3.0 is way faster than any of the old serial connections. USB 3.0 does not keep up.