I have a question regarding CPU processing time on Solaris 11.4 x86 with Intel CPU

I found out that I can measure OpenSSL CPU processing time with the command:

#openssl speed -evp aes-256-cbc -elapsed

On an Intel 9th generation board, it consistently shows as 3 seconds:

Doing aes-256-cbc for 3s on 16 size blocks: 215093065 aes-256-cbc's in 3.00s
Doing aes-256-cbc for 3s on 16 size blocks: 215093065 aes-256-cbc's in 3.00s
Doing aes-256-cbc for 3s on 16 size blocks: 215093065 aes-256-cbc's in 3.00s
Doing aes-256-cbc for 3s on 16 size blocks: 215093065 aes-256-cbc's in 3.00s
Doing aes-256-cbc for 3s on 16 size blocks: 215093065 aes-256-cbc's in 3.00s

But on an Intel 10th generation board, it fluctuates and doesn't stay consistent