There was discussion on one of my previous questions about a "compact" view of the timing diagram where the signal name is left justified and inline with the graphed line instead of above the signal, and the bold horizontal rule that separates each signal in a graph was removed. This would add a lot more compactness to a diagram when needed.
original question. Comments at the bottom.
https://forum.plantuml.net/9053/timing-diagrams-for-binary-signal-and-data-buses