why is tar -czpf very slow under tmux CL9

[oceanwave]

Thanks. I'm logged into the server via ssh as wheel group user, su - to root
#root@server tmux
#root@server tar -czpf file.tar.gz directory...

[oceanwave]

In older cloudlinux versions, I frequently used screen.
Now that there is no screen in CL9, I'm trying to use tmux, but I find a new problem....

[oceanwave]

With no manual config changes with Cloudlinux 9 system, after the latest kernel update and reboot, I got the following email the following night:
...