I have been playing around with cRARk and was astonished by the low speed. On a 2015 high-end GPU (GeForce 980 ti), it took roughly 4h 50min to test all passwords composed of an 8-character prefix and 6 small latin alphabet letters (
AAABBBCC $a * in the format cRARk uses). This is just over 300 million passwords, which corresponds to 18500 passwords per second.
The RAR file is 164 bytes long and has the identification string:
52 61 72 21 1a 07 00
Is it hardware limitation (I've had performance problem with the GPU), is it that cRARk is slow or is it the nature of RAR archives that they are this slow to crack?