I have now played about as much Pathfinder at lvl 10 and up as I have DnD 3.X. So far, I am seeing the same problems...
1) Full attack actions of CR 10, 11, and 12 creatures can RELIABLY kill average, undamaged PCs of similar level.
2) NPC casters of this level can throw around a few save or die effects, giving average NPCs a 50/50 shot of DYING outright.
3) Traps of CR 10, 11, and 12 can RELIABLY kill average, undamaged PCs of similar level.
I love the possibility of PC death as an ever-present concern. Personally, I love to crunch numbers and optimize my characters. At the same time, I respect the other dedicated gamers and role-players at my table who don't try to squeeze and stack every possible bonus. Every time our party gets somewhere between level 9-11, we hit a wall of PC deaths that crash the campaign or slow the action down to an unbearable, almost silly pace. People dying once in a while is cool, and there are ways to deal with it, but someone dying every session is just not fun because continuity is part of the pleasure of this role-playing game.
I am writing this because I believe it to be a system problem, not a player or DM problem. I mentioned that some players in this scenario are not 'optimized,' but they aren't stupid! They give themselves good prime stats and understand that Dex/Con/Wis are all crucial survival stats. Tactically, they aren't perfect, but they know how to concentrate fire, pursue flanks, and avoid attacks of opportunity. Our DM limits the CR of our encounters to our level+1, though most of our encounters are on-level or lower. He also doesn't run monsters 'smarter' or more devious than they should be.
So, the purpose of this post? First, to find out if other groups have similar experiences. Second, to evaluate some possible solutions (mine and yours).
I think the 'HP death point' of PCs needs to be tied to something that increases every level (unlike your Con score).
I also think that the 'full attack action' is an awkward, unbalancing mechanic (I'm not the first one to say it). It is a multiplicative effect rather than an additive one, and that's what makes it SO dangerous.
Finally, save or die effects are cool, but they need to be moderated. For example, maybe they knock you down for that fight on a failed save, but you get additional saves to avoid DEATH.