I heavily recommend a ROM over Stock. My droid runs at moderate speed (won't win any contests, but isn't slow/laggy really badly). Here are the stats:
-> CM 7.1
-> Running at 800 MHz (anything higher would overheat my phone some and often cause issues, especially at 1.25 GHz - YMMV, each hardware has different stress points)
-> Keep AT LEAST 80 MB of ROM storage free (CM uses some virtual memory type of processing help)
-> Have a task killer - I used Task Killer and had it kill apps when I turned off the screen. If I was about to start up a large resource app (Netflix, Navigation, etc) I would always tap the task killer since that would help free up resources. I would usually get a 50 to 60 MB RAM free message from it. You don't need to do it every 5 mintues, but it helps wipe the slate clean to reduce FCs or other response time issues.
Also, I recommend a restart of it weekly, like a regular computer, to help it clear out some running programs.
My Droid, up to the day I upgraded to the Rezound, functioned reasonably well to the point I could proudly say I was running GB on it without whipping out something barely useable with the most recent stuff on it because I barely could (That'll be ICS later
I hope these notes help you.