Currently, the Mechanical Sieve is as fast as a player using a single sieve by hand, without an enchanted mesh. Most players don't know that meshes can be enchanted, so most people see the Mechanical Sieve as an underpowered block. There is another mod called Ex Machinis, made by the ATM team, that powercreeps the Mechanical Sieve to a signficant degree. The Ex Machinis sieve sieves up to 64 blocks at a time in just a matter of seconds, so the Mechanical Sieve needs to be significantly improved in order to compete with this mod.

I'm going to increase the default sieve speed. Adding upgrades was another request, so I'll add multiplier upgrades to the sieve so that multiple blocks can be processed at once, like the Ex Machinis sieve. Adding multiple slots would mean I have to change the GUI code and players would clog their sieves if they tried to sieve several different kinds of blocks at once.

how about adding more sieve slots, use sieve enchantment summary to multiply its speed/product？