Ps cs6 on imac(2011)3,4gh. intel core i7,16gB 1333 mhz ddr,graphic-radeon hd 6970m 2048 mb. since uploade yosemite, programe doesn't run fluently

Question

Hello everybody.
i update to yosemite, ps cs6 extended 13.06 x 64
wont run anymore as fast like before.
the program is slow like in the 90ths.
several function wont work as well.
can t  erase. or the selecting (rectangle) tool wont work in some moments.
getting default messages like, that i selected less than 50 % pixels even if i select the whole screen.
i use a wacom. i update it . not sure if the problem is the hardware.
but before, without yosemite , i was very happy with the program.
can somebody please help.
thanks

Answer 1

i tried out the above link, thanks , and did what the video said.
one thing is solved.
but it sill have some problems with the short cuts.
if i select an area and choose the brush tool to fill out the selection and than choosing , lets say cmd+v , it won't do it.
somehow the program doesn't react as smooth if i'am in the brush mode.
Thank you for your help