Low performance on N2 if kernel version 6.17+

[iav]

After updating the edge kernel to 6.17, and then to 6.18-rc, the performance of my ODroid-N2 dropped drastically.
 
Here are the performance test results of 7zip with different kernel versions for comparison

 

I compile the kernel myself using the armbian build system and install the resulting .deb.

 

'7z b'

 

7-Zip 23.01 (arm64) : Copyright (c) 1999-2023 Igor Pavlov : 2023-06-20
 64-bit arm_v:8 locale=en_GB.UTF-8 Threads:6 OPEN_MAX:1024

Compiler: 13.2.0 GCC 13.2.0
Linux : 6.16.6-edge-meson64 : #1 SMP PREEMPT Tue Sep  9 17:02:41 UTC 2025 : aarch64
PageSize:4KB THP:always hwcap:8FF:CRC32:SHA1:SHA2:AES:ASIMD
LE

1T CPU Freq (MHz):  1901  1897  1904  1904  1904  1904  1903
3T CPU Freq (MHz): 298% 1894   298% 1892

RAM size:    3769 MB,  # CPU hardware threads:   6
RAM usage:   1334 MB,  # Benchmark threads:      6

                       Compressing  |                  Decompressing
Dict     Speed Usage    R/U Rating  |      Speed Usage    R/U Rating
         KiB/s     %   MIPS   MIPS  |      KiB/s     %   MIPS   MIPS

22:       7244   525   1343   7048  |     136762   553   2109  11660
23:       6896   533   1317   7026  |     128222   535   2071  11092
24:       6626   539   1323   7124  |     114197   478   2096  10021
25:       6170   542   1301   7045  |     121553   536   2020  10818
----------------------------------  | ------------------------------
Avr:      6734   535   1321   7061  |     125184   526   2074  10898
Tot:             530   1698   8979

-------------------------------------------------------------------------------------------------

7-Zip 23.01 (arm64) : Copyright (c) 1999-2023 Igor Pavlov : 2023-06-20
 64-bit arm_v:8 locale=en_GB.UTF-8 Threads:6 OPEN_MAX:1024

Compiler: 13.2.0 GCC 13.2.0
Linux : 6.18.0-rc7-edge-meson64 : #1 SMP PREEMPT Sun Nov 23 22:53:16 UTC 2025 : aarch64
PageSize:4KB THP:always hwcap:8FF:CRC32:SHA1:SHA2:AES:ASIMD
LE

1T CPU Freq (MHz):  1966  1985  1732  1940  1979  1946  1486
3T CPU Freq (MHz):  64% 424    97% 641

RAM size:    3773 MB,  # CPU hardware threads:   6
RAM usage:   1334 MB,  # Benchmark threads:      6

                       Compressing  |                  Decompressing
Dict     Speed Usage    R/U Rating  |      Speed Usage    R/U Rating
         KiB/s     %   MIPS   MIPS  |      KiB/s     %   MIPS   MIPS

22:       1045    85   1191   1018  |      20252    91   1903   1727
23:       1078    90   1218   1099  |      18815    86   1889   1628
24:       1100    93   1274   1183  |      19644    92   1880   1724
25:        914    78   1332   1044  |      19697    94   1873   1753
----------------------------------  | ------------------------------
Avr:      1034    87   1253   1086  |      19602    91   1886   1708
Tot:              89   1570   1397

 

 

I have done similar tests on ODroid-M1 (rockchip), but nothing similar happens there.

 

What could be the reason?