Out of curiosity, I gave it a shot. I came out roughly 20% faster using python's inbuilt csv library.

When I switched to pypy the csv library actually made it nearly 2x slower than pypy using .split(delim)

Of course it's faster. Sorry, I wasn't clear. But good luck handling a tab in a quoted field, then.

And you were using the pure Python CSV library, not the C one?

I used the stdlib one, just straight "import csv"

How can you tell?