Issues with 4.11 vs 4.8

There seems to be some things I don’t understand or have changed in 4.11.

  1. When I change lighting I don’t get a preview of what it will look like I have to build the lighting every time, was it like that before?
  2. When I activate Ambient Occlusion my whole scene gets much darker where before it only effected corners of the room etc.
  3. in 4.8 I used 2048 lightmap on my floor, same model, in 4.11 2048 results in bad shadows and receiving bad lighting - I can’t double the lightmap rez my computer crashes.

Thanks for any help!