The trim tabs will help greatly dealing with uneven loads.
With regard to fuel savings and speed, I probably have a different opinion than most.
There are those who think that tabs should rarely be used except when listing needs to be corrected. This view is based on a hull that is well balanced at rest and getting on plane. This view also says that all trimming should be done using the motor trim and tabs shouldn't be used assuming no listing. I kind of agree with the theory.
Often times a hull is not balanced well especially older hulls that had 2 strokes but were repowered with 4 stokes causing the sterns to sit lower in the water. Sometimes you get a boat that has a hard time getting on plane and tabs can help lift its stern.
When deployed, trim tabs add drag. If they reduce the drag of the hull more than they add when deployed, the fuel efficiency goes up. Likewise if you use tabs to push the bow down, that probably adds more overall drag and fuel efficiency goes down. Sometimes you have no choice about where the bow needs to be
In your case when having passengers aboard, tabs can help or actually be needed to get the hull on plane. From a practical aspect, if you need tabs deployed to get the boat on plane and stay there, use as little as possible and when you are on plane reduce tabs as much as possible while still staying on plane. Remember that the motor trim affects performance and it is important it is to learn how to trim your motors for your hull and sea conditions