Designing a Minecraft Redstone Sorter where 64 items every second

Untested - I don't have access to a server with this sort of behavior - but it has a good chance to work - with one big disadvantage of lots of items being "stuck in the system". Precisely, 14 stacks and 37 items. Although with a Looting 47 sword, obtaining enough items to fill the sorters shouldn't be a big problem.

The left side is a standard overflow-proof sorter - the only difference is the lower hopper is nearly full.

The right-side is a 1-tileable auto-dropper that only activates when the dropper is completely full (signal strength 15). The right barrel is empty, so its comparator will give out signal strength 0 as long as the comparator from the dropper doesn't provide signal strength 15. If that happens, the signal strength 15 overrides the state of the empty barrel and the bottom comparator activates the observer clock. This clock then ejects a couple (in my tests - 4) items from the dropper, dropping the signal level below 15 and deactivating the observer clock.

This makes room for 4 items in the dropper - and so it makes the lockable hopper of the sorter able to insert 4 items into the dropper, and pull 4 items from the filter hopper.

And so, at no point is there enough room "downstream" for any of the hoppers to push all 64 items at once, so they will trickle at most at the speed the auto-dropper is clocked.

The barrel below the dropper (one the dropper is pointed into) is there to provide a buffer between the dropper and the output hopper (at the bottom) - otherwise the output hopper would empty the dropper really fast and the whole system would break promptly.

Note: the system uses normal ice for the item iceway, and as such puts restrictions on artificial lighting (daylight OK), or the ice would melt - the ice can't be exposed to light in excess of 10 from any side; it's necessary for the system to be 1-tileable. Ice, being a transparent block, will allow the dropper to be QC-powered but won't activate neighboring ice blocks, not providing QC power to neighbor slice droppers. Opaque blocks like packed ice and blue ice would make three neighboring droppers fire all at once, and eventually break the sorter.