1600 primes/s on 12 core cpu, pays low, is it normal?

Hi,

I have a dedicated server and mining xpm, i get 1600 prime/s , is this normal?

my cpu info:
lscpu
Architecture: x86_64
CPU op-mode(s): 32-bit, 64-bit
Byte Order: Little Endian
CPU(s): 12
On-line CPU(s) list: 0-11
Thread(s) per core: 2
Core(s) per socket: 6
Socket(s): 1
NUMA node(s): 1
Vendor ID: GenuineIntel
CPU family: 6
Model: 45
Stepping: 7
CPU MHz: 2399.924
BogoMIPS: 4799.85
Virtualization: VT-x
L1d cache: 32K
L1i cache: 32K
L2 cache: 256K
L3 cache: 15360K
NUMA node0 CPU(s): 0-11

What I get
[STATS] 2013-12-30 09:07:29 | 1615 primes/s, 26523 tests/s, 300 5-chains/h, 0.045 chains/d
[MASTER] work received
[STATS] 2013-12-30 09:08:29 | 1633 primes/s, 26881 tests/s, 240 5-chains/h, 0.044 chains/d
[STATS] 2013-12-30 09:09:29 | 1662 primes/s, 27429 tests/s, 360 5-chains/h, 0.045 chains/d
[MASTER] work received
[STATS] 2013-12-30 09:10:29 | 1670 primes/s, 27741 tests/s, 240 5-chains/h, 0.045 chains/d
[STATS] 2013-12-30 09:11:29 | 1638 primes/s, 26979 tests/s, 240 5-chains/h, 0.045 chains/d
[STATS] 2013-12-30 09:12:29 | 1688 primes/s, 27964 tests/s, 600 5-chains/h, 0.046 chains/d
[MASTER] work received
[MASTER] work received
[STATS] 2013-12-30 09:13:29 | 1632 primes/s, 26974 tests/s, 660 5-chains/h, 0.045 chains/d
[MASTER] work received

30.12.2013 0.3239 0.0332 XPM/h
29.12.2013 0.2071 0.0086 XPM/h
28.12.2013 0.2437 0.0102 XPM/h
27.12.2013 0.6906 0.0288 XPM/h
26.12.2013 0.3098 0.0129 XPM/h

any idea?