No wonder server is so laggy, this is a horrible design. You can use one piston attached to slime blocks and use one hopper. This is overkill.
a lot of times that design takes up too much space. I tried it and it took me a lot of effort to get it to work
I've made one with pistons and slimeblocks and its pretty compact and works fine. Also I'm terrible at redstone
you can use tripwire hooks to make the pistons activate only when necessary. heres a design using this technique plus the slime block technique ultra lag friendly xd lol note that the block with the redstone torch on it needs to be a furnace to prevent it from being affected by the slime this is just my opinion but i dont think this design takes a whole lot more space than the other one, but you do need plenty of slime to make this, though you dont need as much iron and redstone. this design is just as efficient as the other one.