PreForm Print Time estimation in Form4

Can’t understand Print Time estimation, given this example:

I always want fast prints with minimum spent resin, when optimizing the drawings for SLA I normally orient, draw and build the part for a minimum number of layers, meaning there is a big flat face to adhere the build platform. Normally I try to avoid cups, but when choosing Raft Type to none and Early Layer Merge to 0, strange things start to happen. One of them is print estimation, it’s a lot higher compared to choosing Mini Rafts with many more layers and more resin volume. Cups also tend to appear more with Raft Type option to None. In parts with empty hollow shapes it’s also difficult to remove the inside of the raft, that will never be used to support anything, this is happening in the mini raft case. Also when in Raft Type None, it is impossible to avoid or control the creation of supports that will connect to the build platform.

Any tips optimizing the print of this type of ‘donut’ parts would be great, thanks,
J.Antunes