Marek

I updated the description of this PR, and created #4824. I didn't update the doc file https://github.com/ZcashFoundation/zebra/blob/main/book/src/dev/rfcs/0005-state-updates.md because it seems already outdated. Should I refactor it, and make it up...

> Do you think you can finish this PR this week? Yea, I think I can finish it this week.

I rebased this PR onto #4928, and I'm using the correct treestate now. I resolved all issues, so the PR is ready for another review. I'm running a fresh sync...

I could sync Zebra with this PR, but it still took ~15 hours, so no speedup.

> Is the full verification stage faster? From observing the output log, the last two percent of the sync were still pretty slow.

@mergifyio update

On Friday, I started a full-sync using beta 14 with the following times: - from genesis to block 1705779 (~95.019% of the block chain): 5 hours and 21 minutes -...

Here are times for syncing after the last checkpoint, the height of which is 1789180: This PR: - from block 1789180 to block 1795401: 1 hour, 20 minutes; - the...

> What happens if we're using testnet in a box, or we only have a small number of working peers, but we are actually near the tip? I think checking...

I updated the solution in the PR description with implementation details.