Pathfinder Frustration

We had a frustrating game session. Some of my group seems to be stuck in the "if we see it, we must be able to kill it" mentality of later D&D. This led to disaster. After trouncing everything they had seen so far they ran into a large earth elemental. I tried to give as much warning as possible and had constructed things such that fleeing was very possible. They didn't. While it is possible they could have killed it with some sustained luck they were pretty out matched. Only one survived.

Now a near-TPK in old-school D&D is normal, expected, and easily remedied it comes as a bit of a shock to 3e players who expect to win every fight. Also it takes forever to make characters. SO half the session was spent making new characters. One player failed to even come up with a character concept.

Solution: I am suggesting to players to make at least one backup character. Additionally, I am going to make a pool of backup characters to draw upon. I do not want to have to sit and watch four out of five people agonizing over character options again any time soon.