low performance with prepend more than 3 characters in mask attack

[shadowmourne]

The reason why replacing ?l with the single character "n" results in dramatically lower speed is that the left side of the mask is now too small to gain full acceleration.

but add a character 'n' to the left of original mask also reduce the speed to nearly 28%.

cudaHashcat64.bin  -m 1000 -a 3 b4b9b02e6f09a9bd760f388b67351e2b ?l?l?l?l?l?d?d?d?d?d?d?d
cudaHashcat v1.37 starting...
Device #1: GeForce GTX 680M, 2039MB, 758Mhz, 7MCU

Session.Name...: cudaHashcat
Status.........: Running
Input.Mode.....: Mask (?l?l?l?l?l?d?d?d?d?d?d?d) [12]
Hash.Target....: b4b9b02e6f09a9bd760f388b67351e2b
Hash.Type......: NTLM
Time.Started...: Mon Sep  7 13:11:25 2015 (9 secs)
Time.Estimated.: Tue Sep  8 01:34:53 2015 (12 hours, 23 mins)
Speed.GPU.#1...:  2667.3 MH/s

cudaHashcat64.bin  -m 1000 -a 3 b4b9b02e6f09a9bd760f388b67351e2b n?l?l?l?l?l?d?d?d?d?d?d?d
cudaHashcat v1.37 starting...
Device #1: GeForce GTX 680M, 2039MB, 758Mhz, 7MCU

Session.Name...: cudaHashcat
Status.........: Running
Input.Mode.....: Mask (n?l?l?l?l?l?d?d?d?d?d?d?d) [13]
Hash.Target....: b4b9b02e6f09a9bd760f388b67351e2b
Hash.Type......: NTLM
Time.Started...: Mon Sep  7 13:11:41 2015 (5 secs)
Time.Estimated.: Wed Sep  9 10:36:18 2015 (1 day, 21 hours)
Speed.GPU.#1...:   735.4 MH/s