Assuming you didn't do anything really stupid, that's quite a gap. It could mean that the author implemented it pretty badly. What CPU is it, perhaps I can improve the performance?
24 x Intel Xeon L5639 @ 2.13GHz (2 sockets).
I checked hash rate with http://198.199.79.100 statistics
Okay, er... wut?
24 x Intel Xeon L5639 -- 24 processors? Nah, he probably meant cores; typo
(2 sockets) -- Wait, if he's running two Xeon L5639s... that would be 8 physical cores and 16 threads. Where is 24 coming from?
http://www.cpubenchmark.net/cpu.php?cpu=Intel+Xeon+L5639+%40+2.13GHz&cpuCount=2
Looks like it is 6 physical cores x 2 cpus = 12 physical cores --> 24 threads.