I just changed from LR 5.7.1 to CC6 2015. I have new hard ware and plenty of size, memory processing power. It is so slow I can't manage with it and want to revert to 5.7.1, unfortunately expecting cc 6 2015 to be superior I deleted my5.7.1 V.
I downloaded it again but it asks me for a serial number in order for me to run it. Can I change back, or can I alter settings to improve the performance ofLR 6. I read I should turn off GPU, but I don't know how.