I used metacity --display=:0 --replace in the CTRL+ALT+F1 terminal window to try to speed up the incredibly slow Unity, but instead, Unity crashed. Then I tried unity after launching Terminator (by typing in terminator --display=:0 in that same prompt). That caused Compiz to try to replace Metacity but instead terminated Metacity. Then Compiz and Unity crashed. I had to start Metacity again.