That article is about "AssumeUTXO", SwiftSync is a new proposal from this year.

Is not also what Lopp explain in this article with UTXO snapshot?
https://blog.lopp.net/bitcoin-node-sync-with-utxo-snapshots/

DarthCoin

bitcoin

Quick questions about OP_RETURN? Quick answers here.

tidwell

Good answer, a couple remarks:

1. Embedding data in witnesses does not inherently pollute the UTXO set, but it is often (mis-)used in a way that does. Even worse is data embedded in fake pubkeys or fake pubkey hashes as that data needs to be stored in the UTXO set.

2. You are thinking of [SwiftSync](https://bitcoinops.org/en/newsletters/2025/04/11/#swiftsync-speedup-for-initial-block-download).