Hey Dorian!, Try to Convert a Project Again!, I Converted it AGAIN from 4.14 to 4.15, and Erased all Lights, and Recreated it , and Look at Some Settings of the lights!, May theres a Problem!
After i Converted it Again and Looked at all Settings AO Distance Field Distance etc , I have now DREAM Fps, More FPS than on 4.14!
Like on 4.14 i got 100-110 Fps
on 4.15 i got now 120-140 FPS,
KS