[jonlawlor]

It is kind of both; go doesn't allow some approaches in native go code that can make it slower than other languages. (I love go, but that is my experience.)

In this case the choice to use utf-8 everywhere, including in the csv delimiters, is making it slower.

[weberc2]

This isn't what makes CSV parsing slow, there's nothing about Go that requires you to deal in UTF8.