So, has CVS always been this broken?It doesn't look like it. At least some versions of CVS use far more sensible code: https://github.com/openbsd/src/blob/56696e8786be09c79aaaadb09d99b103c314f835/gnu/usr.bin/cvs/src/buffer.c#L92This code doesn't suffer from the "two lists" syndrome, so it remains fast no matter what. It allocates 16 pages at a time. It never frees the memory and just keeps it in a list to be reused when the need arises.