So, as the title says, here they are:
1) Do something about the items that are beyond the players screen. For example, when you generate a new world then a lot of structures start replacing the blocks around them/each other and as a result the blocks drop as items, which results in lags. I've seen it happen after generating a world and drinking a Ceaseless Hunger Potion from calamity, from my prediction, the items keep being simulated even at the world borders, which has basically no upsides for the player and just lags the game.
2) I'd suggest looking at the "Lag Remover" mod and borrowing a couple of features from there, for example the sliders which determine whether gore/dust/combat text shows during boss battles and such, chance to remove dust and the falling stars gen removal.
3) Make the description of the current options clearer, like for example the "Dust & Projectile distance", what is 35 distance? 35 pineapples? 35 apples?
that's pretty much it, thank you for your time