I never understood why XFCE is not the default for Ubuntu desktop. It was(is?) part of Xubuntu, the lightweight Ubuntu distro, years ago. I had the most basic entry level laptop, but I managed to connect 2 external monitors to it while the tiling would remember the locations of all programs in all three monitors and it was FAST. Nothing I have tried since has touched it. It set me up for a lot of disappointment! I now have a macbook and while it's a great and integrated machine, CMD-tab - which I use to switch screens - doesn't even work properly if an application is in fullscreen mode.