Hashcat slows down after starting attack

[174region174]

Hi,

I'm search why hashcat slows down after staring attack, but I cannot find the solution on the forum. 
Mode -22000, it starts with normal speed 652.3 kH/s but after some seconds speed goes down and stabilize to about 400.0 kH/s.
Can someone tell me why?
Thank you

Code:

CUDA API (CUDA 12.7)
====================
* Device #1: NVIDIA GeForce GTX 1080 Ti, 10202/11263 MB, 28MCU

OpenCL API (OpenCL 3.0 CUDA 12.7.29) - Platform #1 [NVIDIA Corporation]
=======================================================================
* Device #2: NVIDIA GeForce GTX 1080 Ti, skipped

OpenCL API (OpenCL 3.0 WINDOWS) - Platform #2 [Intel(R) Corporation]
====================================================================
* Device #3: Intel(R) Xeon(R) Gold 6130 CPU @ 2.10GHz, skipped

Minimum password length supported by kernel: 8
Maximum password length supported by kernel: 63

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
* Slow-Hash-SIMD-LOOP

Watchdog: Temperature abort trigger set to 85c

Host memory required for this attack: 872 MB

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

Session..........: 2024-11-20
Status...........: Running
Hash.Mode........: 22000 (WPA-PBKDF2-PMKID+EAPOL)
Hash.Target......: E:\hashcat\pmkid_test.22000
Time.Started.....: Wed Nov 20 09:56:59 2024 (1 sec)
Time.Estimated...: Wed Nov 20 14:12:29 2024 (4 hours, 15 mins)
Kernel.Feature...: Pure Kernel
Guess.Mask.......: ?1?1?1?1?1?1?1?1?1?1 [10]
Guess.Charset....: -1 ?d, -2 Undefined, -3 Undefined, -4 Undefined
Guess.Queue......: 1/1 (100.00%)
Speed.#1.........:  652.3 kH/s (85.32ms) @ Accel:16 Loops:1024 Thr:512 Vec:1
Recovered........: 0/1 (0.00%) Digests (total), 0/1 (0.00%) Digests (new)
Progress.........: 229376/10000000000 (0.00%)
Rejected.........: 0/229376 (0.00%)
Restore.Point....: 229376/10000000000 (0.00%)
Restore.Sub.#1...: Salt:0 Amplifier:0-1 Iteration:0-1
Candidate.Engine.: Host Generator + PCIe
Candidates.#1....: 1234567899 -> 4664252345
Hardware.Mon.#1..: Temp: 59c Fan: 56% Util: 99% Core:1860MHz Mem:5200MHz Bus:16

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

Session..........: 2024-11-20
Status...........: Running
Hash.Mode........: 22000 (WPA-PBKDF2-PMKID+EAPOL)
Hash.Target......: E:\hashcat\pmkid_test.22000
Time.Started.....: Wed Nov 20 09:56:59 2024 (5 secs)
Time.Estimated...: Wed Nov 20 16:07:45 2024 (6 hours, 10 mins)
Kernel.Feature...: Pure Kernel
Guess.Mask.......: ?1?1?1?1?1?1?1?1?1?1 [10]
Guess.Charset....: -1 ?d, -2 Undefined, -3 Undefined, -4 Undefined
Guess.Queue......: 1/1 (100.00%)
Speed.#1.........:  449.5 kH/s (86.02ms) @ Accel:16 Loops:1024 Thr:512 Vec:1
Recovered........: 0/1 (0.00%) Digests (total), 0/1 (0.00%) Digests (new)
Progress.........: 1605632/10000000000 (0.02%)
Rejected.........: 0/1605632 (0.00%)
Restore.Point....: 1605632/10000000000 (0.02%)
Restore.Sub.#1...: Salt:0 Amplifier:0-1 Iteration:3072-4095
Candidate.Engine.: Host Generator + PCIe
Candidates.#1....: 2154530000 -> 8803471234
Hardware.Mon.#1..: Temp: 58c Fan: 55% Util: 70% Core:1860MHz Mem:5200MHz Bus:16

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

Session..........: 2024-11-20
Status...........: Running
Hash.Mode........: 22000 (WPA-PBKDF2-PMKID+EAPOL)
Hash.Target......: E:\hashcat\pmkid_test.22000
Time.Started.....: Wed Nov 20 09:56:59 2024 (10 secs)
Time.Estimated...: Wed Nov 20 16:28:21 2024 (6 hours, 31 mins)
Kernel.Feature...: Pure Kernel
Guess.Mask.......: ?1?1?1?1?1?1?1?1?1?1 [10]
Guess.Charset....: -1 ?d, -2 Undefined, -3 Undefined, -4 Undefined
Guess.Queue......: 1/1 (100.00%)
Speed.#1.........:  425.9 kH/s (86.10ms) @ Accel:16 Loops:1024 Thr:512 Vec:1
Recovered........: 0/1 (0.00%) Digests (total), 0/1 (0.00%) Digests (new)
Progress.........: 4128768/10000000000 (0.04%)
Rejected.........: 0/4128768 (0.00%)
Restore.Point....: 4128768/10000000000 (0.04%)
Restore.Sub.#1...: Salt:0 Amplifier:0-1 Iteration:0-1
Candidate.Engine.: Host Generator + PCIe
Candidates.#1....: 2983741234 -> 8198990000
Hardware.Mon.#1..: Temp: 59c Fan: 55% Util:100% Core:1860MHz Mem:5200MHz Bus:16

Remove the -S option from your command line at startup. I see that you have it present. In a wpa attack, this option is only needed when working with applying rules to a dictionary.