My experience is opposite what many people have said. If I'm making a PC to play, I can whip it out in about 30 min since I have a "stable" of character concepts floating around in my head at any time. On the other hand if I'm making a major NPC it typically takes me an hour or more since I generally have to start from scratch. Minor npcs range from 15 min to on the spot. As a rule of thumb I just double the BAB of any minor non-spellcaster and apply the typical class modifiers (sneak attack for instance). Spellcasters, no matter how minor take at least 15 min due to the spell list, and that is if they are extremely minor and low level.
I tend to agonize a bit over npc equipment, I want it to be more than just cash to the party, "Oh, another pair of ogre gauntlets, throw them on the pile." I'm currently trying to write some equipment guidelines for the different classes to speed up item selection. Something like "Fighter: 33% armor/shield, 25% weapon, 22% enhancement, 10% special, 10% expendable" I need to get another copy of vis studio so I can go back to working on my npc generator