Hi Deck,
Thanks a lot for taking a look!
I originally modeled the bottle with an inner surface + liquid. However in my search for an alpha sweet spot I removed everything else. Being fully well aware that not having that geometry will eliminate any proper refraction etc. Those points are leftover from that. I obviously missed optimizing the scene sorry.
As you say I should go back to my original model so that it is physically correct I think. I will experiment further with absorption color, thanks.
The bottle is animated in the actual scene but I think your suggestion about different passes for color and alpha is probably also another way forward, with more steps however.
Again, thank you for your time.
MJ