Designing a Minecraft Redstone Sorter where 64 items in a stack go through hoppers each tick

Solution 1:

The only reliable way to deal with such huge throughput of items with a sorter, is parallellizing.

Transport the items using water streams. Align them to the edge of the line of hoppers using sea pickles or chests. These hoppers would be the "middle" hoppers from the standard overflow-proof sorter design by ImpulseSV (you use water stream instead of the top line of hoppers). Obviously after short initial period when filling up, every sorter will only be able to take just one item per 8 game ticks (4 redstone ticks), so if you have 64 items per game tick, your sorter will need to be 256 blocks long - per one item type! - you just need to configure as many sorters (in parallel) to take the same type of the item that there are enough to capture and process the entire input.

Obviously transporting this out through any conventional means like hoppers or dropper lines or even minecarts would be completely impractical, so the bottom hoppers should be emptying into 1-tileable auto-droppers ejecting sorted items into a water stream, one stream per item type. You can similarly align the sorted items and use rows of hoppers to put them into storage.

ps. verify if it's really 64 items per tick sustained, because that's a pretty insane rate and while the above solution will work with it, it's really not practical - nothing is practical with this sort of rates. If it's just short bursts of large amounts of items, it might be smarter to limit the throughput and even it out a bit - snarf the items into a buffer then gradually eject through some auto-droppers.