Q regarding increase of step rate on macbook pro 13''

Am running a 13'' macbook pro 2010 with 2.66 ghz and a geforce 320M graphics card. Is there a way to increase the overall speed of the cuda multiforcer ie the step rate or is that all I get (my current step count is 23M as you may see below in the info output)?
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info:
admin davids-MacBook-Pro:cuda thegray$ ./cuda-multiforcer -c charsets/charsetfull -f test_hashes/hashes.txt --min 4 --max 11 -h MD5
Cryptohaze.com CUDA Multiforcer (multiple hash brute forcer)
by Bitweasil
Version 0.72, length 0-14
Currently supported hash types: MD5 FASTMD5 MD4 FASTMD4 NTLM FASTNTLM SHA1 FASTSHA1
Hash type: MD5
CUDA Device Information:
Device 0: "GeForce 320M"
Number of cores: 48
Clock rate: 0.95 GHz
Performance Number: 5700
Note: Performance number is clock in mhz * core count, for comparing devices.
Single charset loaded.
Loading & sorting hashes. This may take a while.
Hashes loaded (6 hashes)
You may want to consider the FAST[hash] option if it exists.
Launching kernel for password length 4
Done: 80.98% Step rate: 23.7M/s Search rate: 142.3M/sec
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Compute done: Reference time 5.8 seconds
Stepping rate: 18.7M MD4/s
Search rate: 112.1M NTLM/s
Launching kernel for password length 5
Done: 100.00% Step rate: 23.2M/s Search rate: 139.2M/sec
----------
info:
admin davids-MacBook-Pro:cuda thegray$ ./cuda-multiforcer -c charsets/charsetfull -f test_hashes/hashes.txt --min 4 --max 11 -h MD5
Cryptohaze.com CUDA Multiforcer (multiple hash brute forcer)
by Bitweasil
Version 0.72, length 0-14
Currently supported hash types: MD5 FASTMD5 MD4 FASTMD4 NTLM FASTNTLM SHA1 FASTSHA1
Hash type: MD5
CUDA Device Information:
Device 0: "GeForce 320M"
Number of cores: 48
Clock rate: 0.95 GHz
Performance Number: 5700
Note: Performance number is clock in mhz * core count, for comparing devices.
Single charset loaded.
Loading & sorting hashes. This may take a while.
Hashes loaded (6 hashes)
You may want to consider the FAST[hash] option if it exists.
Launching kernel for password length 4
Done: 80.98% Step rate: 23.7M/s Search rate: 142.3M/sec
------------------------------------------
Compute done: Reference time 5.8 seconds
Stepping rate: 18.7M MD4/s
Search rate: 112.1M NTLM/s
Launching kernel for password length 5
Done: 100.00% Step rate: 23.2M/s Search rate: 139.2M/sec