why Hashcat v6.2.6 is slower than v4.1.0 (or 5.1.0)

[Noema]

Why hashcat v6.2.6 is slower than v4.1.0 with same GPU? Here is my test result.

hashcat v4.1.0 result:

Code:

 
sudo ./hashcat64.bin -m 500 *********** -a 3 -1 ?l?u?d ?1?1?1?1?1?1 -w 3
hashcat (v4.1.0) starting...

OpenCL Platform #1: NVIDIA Corporation
======================================
* Device #1: NVIDIA GeForce RTX 2080, 1995/7982 MB allocatable, 46MCU
* Device #2: NVIDIA GeForce RTX 2080, 1995/7982 MB allocatable, 46MCU
* Device #3: NVIDIA GeForce RTX 2080, 1995/7982 MB allocatable, 46MCU
* Device #4: NVIDIA GeForce RTX 2080, 1995/7982 MB allocatable, 46MCU
* Device #5: NVIDIA GeForce RTX 2080, 1995/7982 MB allocatable, 46MCU
* Device #6: NVIDIA GeForce RTX 2080, 1995/7982 MB allocatable, 46MCU
* Device #7: NVIDIA GeForce RTX 2080, 1995/7982 MB allocatable, 46MCU
* Device #8: NVIDIA GeForce RTX 2080, 1995/7982 MB allocatable, 46MCU

OpenCL Platform #2: Intel(R) Corporation
========================================
* Device #9: Intel(R) Xeon(R) CPU E5-2678 v3 @ 2.50GHz, skipped.

Hashes: 1 digests; 1 unique digests, 1 unique salts
Bitmaps: 16 bits, 65536 entries, 0x0000ffff mask, 262144 bytes, 5/13 rotates

Applicable optimizers:
* Zero-Byte
* Single-Hash
* Single-Salt
* Brute-Force

Minimum password length supported by kernel: 0
Maximum password length supported by kernel: 256

ATTENTION! Pure (unoptimized) OpenCL kernels selected.
This enables cracking passwords and salts > length 32 but for the price of drastically reduced performance.
If you want to switch to optimized OpenCL kernels, append -O to your commandline.

Watchdog: Temperature abort trigger set to 90c

[s]tatus [p]ause [b]ypass [c]heckpoint [q]uit => s

Session..........: hashcat
Status...........: Running
Hash.Type........: md5crypt, MD5 (Unix), Cisco-IOS $1$ (MD5)
Hash.Target......: ***********
Time.Started.....: Wed Sep 14 14:30:13 2022 (9 secs)
Time.Estimated...: Wed Sep 14 14:43:17 2022 (12 mins, 55 secs)
Guess.Mask.......: ?1?1?1?1?1?1 [6]
Guess.Charset....: -1 ?l?u?d, -2 Undefined, -3 Undefined, -4 Undefined
Guess.Queue......: 1/1 (100.00%)
Speed.Dev.#1.....:  9123.7 kH/s (77.35ms) @ Accel:1024 Loops:500 Thr:32 Vec:1
Speed.Dev.#2.....:  9200.9 kH/s (76.63ms) @ Accel:1024 Loops:500 Thr:32 Vec:1
Speed.Dev.#3.....:  8775.6 kH/s (80.42ms) @ Accel:1024 Loops:500 Thr:32 Vec:1
Speed.Dev.#4.....:  8776.2 kH/s (80.52ms) @ Accel:1024 Loops:500 Thr:32 Vec:1
Speed.Dev.#5.....:  9176.8 kH/s (76.85ms) @ Accel:1024 Loops:500 Thr:32 Vec:1
Speed.Dev.#6.....:  9090.1 kH/s (77.61ms) @ Accel:1024 Loops:500 Thr:32 Vec:1
Speed.Dev.#7.....:  9137.9 kH/s (77.24ms) @ Accel:1024 Loops:500 Thr:32 Vec:1
Speed.Dev.#8.....:  9101.5 kH/s (77.55ms) @ Accel:1024 Loops:500 Thr:32 Vec:1
Speed.Dev.#*.....: 72355.5 kH/s
Recovered........: 0/1 (0.00%) Digests, 0/1 (0.00%) Salts
Progress.........: 649658368/56800235584 (1.14%)
Rejected.........: 0/649658368 (0.00%)
Restore.Point....: 0/916132832 (0.00%)
Candidates.#1....: Warier -> WMPoba
Candidates.#2....: VbEhAN -> VnWGst
Candidates.#3....: IN8My1 -> IApQda
Candidates.#4....: I9WGst -> IVqUan
Candidates.#5....: VSIYMA -> VkbMon
Candidates.#6....: WOYdce -> W0jX69
Candidates.#7....: V5eYKI -> VZV0er
Candidates.#8....: VX5k45 -> VqMb56
HWMon.Dev.#1.....: Temp: 70c Fan: 38% Util: 99% Core:1815MHz Mem:6800MHz Bus:16
HWMon.Dev.#2.....: Temp: 69c Fan: 38% Util: 99% Core:1845MHz Mem:6800MHz Bus:16
HWMon.Dev.#3.....: Temp: 73c Fan:136% Util: 99% Core:1785MHz Mem:6800MHz Bus:16
HWMon.Dev.#4.....: Temp: 74c Fan:132% Util: 99% Core:1815MHz Mem:6800MHz Bus:16
HWMon.Dev.#5.....: Temp: 69c Fan:133% Util: 99% Core:1845MHz Mem:6800MHz Bus:8
HWMon.Dev.#6.....: Temp: 76c Fan: 43% Util: 99% Core:1830MHz Mem:6800MHz Bus:16
HWMon.Dev.#7.....: Temp: 73c Fan: 41% Util:100% Core:1815MHz Mem:6800MHz Bus:16
HWMon.Dev.#8.....: Temp: 68c Fan: 37% Util: 99% Core:1815MHz Mem:6800MHz Bus:4

hashcat v6.2.6 result:

Code:

sudo ./hashcat.bin -m 500 *********** -a 3 -1 ?l?u?d ?1?1?1?1?1?1 -w 3
hashcat (v6.2.6) starting
OpenCL API (OpenCL 3.0 CUDA 11.7.89) - Platform #1 [NVIDIA Corporation]
=======================================================================
* Device #1: NVIDIA GeForce RTX 2080, 7808/7982 MB (1995 MB allocatable), 46MCU
* Device #2: NVIDIA GeForce RTX 2080, 7808/7982 MB (1995 MB allocatable), 46MCU
* Device #3: NVIDIA GeForce RTX 2080, 7808/7982 MB (1995 MB allocatable), 46MCU
* Device #4: NVIDIA GeForce RTX 2080, 7808/7982 MB (1995 MB allocatable), 46MCU
* Device #5: NVIDIA GeForce RTX 2080, 7808/7982 MB (1995 MB allocatable), 46MCU
* Device #6: NVIDIA GeForce RTX 2080, 7808/7982 MB (1995 MB allocatable), 46MCU
* Device #7: NVIDIA GeForce RTX 2080, 7808/7982 MB (1995 MB allocatable), 46MCU
* Device #8: NVIDIA GeForce RTX 2080, 7808/7982 MB (1995 MB allocatable), 46MCU

OpenCL API (OpenCL 2.1 LINUX) - Platform #2 [Intel(R) Corporation]
==================================================================
* Device #9: Intel(R) Xeon(R) CPU E5-2678 v3 @ 2.50GHz, skipped

Minimum password length supported by kernel: 0
Maximum password length supported by kernel: 256

Hashes: 1 digests; 1 unique digests, 1 unique salts
Bitmaps: 16 bits, 65536 entries, 0x0000ffff mask, 262144 bytes, 5/13 rotates

Optimizers applied:
* Zero-Byte
* Single-Hash
* Single-Salt
* Brute-Force

ATTENTION! Pure (unoptimized) backend kernels selected.
Pure kernels can crack longer passwords, but drastically reduce performance.
If you want to switch to optimized kernels, append -O to your commandline.
See the above message to find out about the exact limits.

Watchdog: Temperature abort trigger set to 90c

Host memory required for this attack: 11714 MB

Cracking performance lower than expected?               

* Append -O to the commandline.
  This lowers the maximum supported password/salt length (usually down to 32).

* Append -S to the commandline.
  This has a drastic speed impact but can be better for specific attacks.
  Typical scenarios are a small wordlist but a large ruleset.

* Update your backend API runtime / driver the right way:
  https://hashcat.net/faq/wrongdriver

* Create more work items to make use of your parallelization power:
  https://hashcat.net/faq/morework

[s]tatus [p]ause [b]ypass [c]heckpoint [f]inish [q]uit => s

Session..........: hashcat
Status...........: Running
Hash.Mode........: 500 (md5crypt, MD5 (Unix), Cisco-IOS $1$ (MD5))
Hash.Target......: ***********
Time.Started.....: Wed Sep 14 14:32:15 2022 (56 secs)
Time.Estimated...: Wed Sep 14 15:50:06 2022 (1 hour, 16 mins)
Kernel.Feature...: Pure Kernel
Guess.Mask.......: ?1?1?1?1?1?1 [6]
Guess.Charset....: -1 ?l?u?d, -2 Undefined, -3 Undefined, -4 Undefined
Guess.Queue......: 1/1 (100.00%)
Speed.#1.........:  1526.2 kH/s (30.50ms) @ Accel:32 Loops:1000 Thr:32 Vec:1
Speed.#2.........:  1571.1 kH/s (29.71ms) @ Accel:32 Loops:1000 Thr:32 Vec:1
Speed.#3.........:  1473.4 kH/s (31.85ms) @ Accel:32 Loops:1000 Thr:32 Vec:1
Speed.#4.........:  1465.5 kH/s (32.39ms) @ Accel:32 Loops:1000 Thr:32 Vec:1
Speed.#5.........:  1497.1 kH/s (31.43ms) @ Accel:32 Loops:1000 Thr:32 Vec:1
Speed.#6.........:  1522.2 kH/s (30.75ms) @ Accel:32 Loops:1000 Thr:32 Vec:1
Speed.#7.........:  1536.3 kH/s (30.41ms) @ Accel:32 Loops:1000 Thr:32 Vec:1
Speed.#8.........:  1567.9 kH/s (29.62ms) @ Accel:32 Loops:1000 Thr:32 Vec:1
Speed.#*.........: 12159.7 kH/s
Recovered........: 0/1 (0.00%) Digests (total), 0/1 (0.00%) Digests (new)
Progress.........: 676413440/56800235584 (1.19%)
Rejected.........: 0/676413440 (0.00%)
Restore.Point....: 10362880/916132832 (1.13%)
Restore.Sub.#1...: Salt:0 Amplifier:4-5 Iteration:0-1000
Restore.Sub.#2...: Salt:0 Amplifier:57-58 Iteration:0-1000
Restore.Sub.#3...: Salt:0 Amplifier:4-5 Iteration:0-1000
Restore.Sub.#4...: Salt:0 Amplifier:57-58 Iteration:0-1000
Restore.Sub.#5...: Salt:0 Amplifier:32-33 Iteration:0-1000
Restore.Sub.#6...: Salt:0 Amplifier:0-1 Iteration:0-1000
Restore.Sub.#7...: Salt:0 Amplifier:16-17 Iteration:0-1000
Restore.Sub.#8...: Salt:0 Amplifier:54-55 Iteration:0-1000
Candidate.Engine.: Device Generator
Candidates.#1....: bJCAda -> bUnrST
Candidates.#2....: YGLFy1 -> Yx7oKI
Candidates.#3....: bzfnJA -> byDrST
Candidates.#4....: Y8VOve -> YKKTQU
Candidates.#5....: MpE5GI -> MhXuBO
Candidates.#6....: stMGba -> srWrST
Candidates.#7....: g2IfIE -> gWatTA
Candidates.#8....: WRKPXX -> WcAuBO
Hardware.Mon.#1..: Temp: 69c Fan:129% Util:100% Core:1830MHz Mem:6800MHz Bus:16
Hardware.Mon.#2..: Temp: 83c Fan: 52% Util:100% Core:1710MHz Mem:6800MHz Bus:16
Hardware.Mon.#3..: Temp: 73c Fan:136% Util:100% Core: 907MHz Mem:6800MHz Bus:16
Hardware.Mon.#4..: Temp: 74c Fan:132% Util:100% Core: 922MHz Mem:6800MHz Bus:16
Hardware.Mon.#5..: Temp: 69c Fan:132% Util:100% Core:1860MHz Mem:6800MHz Bus:8
Hardware.Mon.#6..: Temp: 78c Fan:137% Util:100% Core:1815MHz Mem:6800MHz Bus:16
Hardware.Mon.#7..: Temp: 72c Fan:137% Util:100% Core:1860MHz Mem:6800MHz Bus:16
Hardware.Mon.#8..: Temp: 80c Fan:135% Util:100% Core:1815MHz Mem:6800MHz Bus:4

Do not tell me use optimized kernel, and i don't want to use -O parameter, i want to know the reason in pure kernel mode.