Fgetcsv in php incredibly slow

Yesterday, all of a sudden the php function fgetcsv started performing very slowly in a while loop.
The last 2 iterations of the loop take 1 (plus a second or so) minute each.

I didn’t change anything, and a buddy of mine is using the same setup I have on another Windows machine, and it’s not behaving like that for him.

Anyone have any insights as to what might be causing this?