Peace and Good Again (now with a solution for the use of Firefox and Thunderbird toguether)
first of all
purple.disable_foreground_integration
Change to true

toolkit.cosmeticAnimations.enabled
change to false

mail.spotlight.enable
change to false

browser.tabs.unloadOnLowMemory
change to false

dom.ipc.processCount
change to 1 or 2

accessibility.force_disabled
change to 1

widget.use-dbus-menu
change to false

browser.tabs.remote.autostart
change to true

widget.use-dbus-menu
change to false

Change the ahead lines in Thunderbird (configuration -engine icon, then scroll down at config editor, advanced preferences) too, and also change that lines:
gfx.webrender.software
change to true

layers.acceleration.disabled
change to true

webgl.disabled
change to true

gfx.x11-egl.force-disabled
change to true

widget.gtk.cursor-async.enabled
change to false

so trhe lines doenst do the work alone, at least for me. Indeed in this case i need to change some lines to configure the rendering method.

nano /usr/share/applications/firefox-esr.desktop
Exec=env -i DISPLAY=:0 dbus-run-session /usr/lib/firefox-esr/firefox-esr %u

nano /usr/share/applications/thunderbird.desktop
Exec=env -i DISPLAY=:0 dbus-run-session /usr/bin/thunderbird %u

And now i m  thinking if changing only the archive /usr/share/applications/firefox-esr.desktop i can get stop the freezes??? Anyone can test, and report? (im thinking in test too hhehehe).