When we think about factors determining our choice of Starter theme how often do we think of performance? I'd hazard a guess very few consider factors such as database queries and memory usage, whereas we are more inclined to be interested in ease of theming, documentation and support.
These tests compare 6 Drupal starter themesâ€”Stark, Framework, Ninesixty, Zen and both Genesis starter subthemes (6.x-2.x-dev). For these tests each theme was in "live production mode", meaning that any registry rebuild features were disabled and for Ninesixty the debug stylesheet was unset.
Those things aside this is at least an interesting comparison and I hope to encourage you to factor in performance when making your starter theme selection.