I live at 7500 ft and have no problems some things take a little longer.I also cooked every summer for 8 years at 10.000 ft and at the Taos Ski Valley for 11 years in the winter 9.500 ft.It just takes longer never had any problems with breads,cookies only cakes can be some what difficult.The bright side is you you are not likely to burn anything.It definatly can take forever to cook beans even though they are soaked in Texas Im always shocked how quickly a pot of beans will cook even without soaking.
Any thing under 3000 ft should be no problem.