> primarily they should be compact
As Walter said, Times is already very economical.
If you're sure you need to cram more, then I think
you have two options:
1) Use a font with a bigger x-height at a smaller size.
You'll lose some readability compared to a font with
a decent x-height at a decent size, but not as much
as that font simply set smaller.
2) If your text has a lot of linebreaks, a *wider*
font set at a smaller size will save more space.