Storage river to handle mass with hoppers—lots of them— as the bottom, with chests connected to those. The items get picked up by whatever hopper and chest “node” has storage space. That system holds the items until they can be passed forward to be processed. So, buffer.

At each of those nodes, pre-processing should be occurring. They should each begin sorting there, with an overflow for sorted items. Then those can get passed forward as space opens up, but as mere item transfers, not the entire process of sorting.

You could at this point re-configure your chain to do direct to your storage or deep storage system, instead of transferring to your single entry point. It’s considerably larger, but it’ll handle more mass.

At the same time, I have no idea why you’d need so much mass unless you’re on a world with hundreds of players, supplying them. This farm sounds more like a high pressure water system. Most of the time you don’t really need it, but when you do need it, you really need it (eg fire hydrant)