If you love GNOME 3 but the animations are really sluggish on an older machine (driving you crazy) then you can disable them using dconf-editor (install that first).
In dconf-editor, browse to org.gnome.desktop.interface and set enable-animations=false.
You can also run this command to disable animations:
gsettings set org.gnome.desktop.interface enable-animations false
And re-enable animations with true:
gsettings set org.gnome.desktop.interface enable-animations true
You do not need to log out and back in, it should take effect immediately.
I hope that stops someone from un-installing GNOME on an older machine…