If that was true, then there wouldn’t be database clients that are 100% faster than competitor clients and web servers that are several hundred % faster than sl

If that was true, then there wouldn’t be database clients that are 100% faster than competitor clients and web servers that are several hundred % faster than slower ones, don’t you think? “IO therefor slow” is a “myth”. IO is slow, but the 1,000 millisecond request times from the server you’re sitting beside is not slow because of IO. When experts say “IO is slow”, they’re not saying that you should therefor disregard all semblance of performance characteristics for anything touching IO. They are saying that you should batch your IO so that instead of doing hundreds of IO calls, you do 1 instead.