SSH forwarding - x server display remote program on local machine

Two debian machines

Debian 10 Kali Linux 2020 rolling

lak:~# sudo ssh -XC [email protected]

works to forward specific programs like firefox, nautilus

connected via ethernet lan

Things noticed

• Nautilus works with only a slight lag compared to local desktop x display of nautilus,

• Firefox lags so user can not enter settings, unsuably slow response, hangs on X ing out of browser window.

• GNUcash works perfectly - no lag no problems closing or 'X-ing' out

• using the ssh -C switch for compression but that does not help.

• two network cards on both machines so both machines can apt-get update while also connected by ssh on separate eth0 card. so both machines have tested internet connection

Any suggestions to make programs like firefox usable through ssh forwarding?