Should I enable or unenable hardware acceleration in the browser?

Devuan's Firefox cannot use hardware acceleration under X. The button is lying to you.

The picom developers strongly recommend using the TearFree option for the Intel & AMD DDX drivers and the FullForceComposition pipeline can be used for the NVIDIA blob but if you're using nouveau or modesetting this is not an option.

EDIT: I strongly recommend using Wayland instead because it has completely solved the tearing problem and it does so without the atrocious drag lag that TearFree (and compton/picom) cause in X.

#backend = "xrender";
backend = "glx";

but I sill am experiencing terrible screen tearing. Should I enable or unenable hardware acceleration in the browser? Is there anything else to try?

EDIT
Hardware acceleration was off, so I switched it on. Screen tearing is still bad.

But I can only find this:

Just create a fresh configuration file in $HOME with the correct backend value assigned. It should override the default defined in the sample file.

Yes. The package information for compton recommends switching to picom instead.

backend = "xrender";
#backend = "glx";

and change them to

#backend = "xrender";
backend = "glx";

But I can only find this:

# Other
backend = "xrender";
mark-wmwin-focused = true;
mark-ovredir-focused = true;
# use-ewmh-active-win = true;
detect-rounded-corners = true;
detect-client-opacity = true;
refresh-rate = 0;
vsync = "none";
dbe = false;
paint-on-overlay = true;
# sw-opti = true;
# unredir-if-possible = true;
# unredir-if-possible-delay = 5000;
# unredir-if-possible-exclude = [ ];
focus-exclude = [ "class_g = 'Cairo-clock'" ];
detect-transient = true;
detect-client-leader = true;
invert-color-include = [ ];
# resize-damage = 1;
 
# GLX backend
# glx-no-stencil = true;
glx-copy-from-front = false;
# glx-use-copysubbuffermesa = true;
# glx-no-rebind-pixmap = true;
glx-swap-method = "undefined";
# glx-use-gpushader4 = true;
# xrender-sync = true;
# xrender-sync-fence = true;

Regarding what hevidevi wrote, is that the case? I still have picom installed. Should I delete one or the other? The whole reason for this is that I have big time screen tearing in my browser.

Looks like both binaries are in stable.

when I click on .deb files to install apps, instead of installing they open with the archiver

Add this line to ~/.config/mimeapps.list:

application/x-deb=gdebi.desktop

Debian packages will not alter the contents of $HOME, to do so is in violation of official Debian policy. This also applies to Devuan (and most other distributions).

Use this to list the package contents:

dpkg -L compton

There is a sample configuration file provided. See if you can find it.

The second issue is I installed Compton because of screen tearing in the browser. The instructions I was given said after installing it to go to /home/**/.config and open compton.conf and edit some lines. The problem is this file doesn't exit. I double checked and made sure Compton is installed and was added to the list of start up apps, but no config file for it exists.