I think now it is a good time to start new round of Ergo node bootstrapping optimizations. The goal would be to keep bootstrapping time under 3-4 hours on commodity hardware (e.g. laptops with 8GB RAM and 30 Mbps download speed), and also reduce memory footprint. I am already doing some work towards that.
The plan would be as follows:
avoid unnecessary (de)serializations and allocations. I already eliminated unnecessary Header deserializations during sync network message construction in this PR: P2P layer optimizations - part I by kushti · Pull Request #1290 · ergoplatform/ergo · GitHub . Also, passing ergoTreeBytes instead of ErgoTree in ErgoBox ( Avoid duplicates of ErgoTrees and Constants · Issue #694 · ScorexFoundation/sigmastate-interpreter · GitHub ) would help to avoid unnecessary tree construction when we just need to e.g. pass block transactions to a peer. Even more, we can just read bytes and pass them to the network with no doing serialization & deserialization on the way.
like in Bitcoin Core, we can avoid signature and cost validation for old blocks. Unlike Bitcoin Core, no need to hard-code state commitment checkpoints as with UTXO-set commitments we have state checkpoints written down into each block-header. I think at the moment we can skip validation for all the V1 blocks (so before 417,792). There will be a flag to skip sigs validation (enabled by default), so it will be possible to do sig validation if a user is willing to do so.
avoid state versioning for old blocks
Should be enough for now, along with P2P layer improvements, then we can add bootstrapping with UTXO-set snapshot, nipopows, more efficient storage implementation for AVL+ tree authenticating UTXO set, JIT+AOT costing instead of just AOT, simplified interpreter etc.