Efficiency in managing data stored in Bitcoin nodes continues to be an interest of the protocol developers. A new proposal in this regard is Assumeutxo, which reduces storage loads for nodes using serialized UTXO (unspent output transactions).

In the proposal devised by James O'Beirne, a developer on the OpenSats team, it is detailed that Assumeutxo "reduces the amount of time necessary to start a usable Bitcoin node with acceptable security changes." The development targets people who want to run a full Bitcoin node; that is, one that stores a copy of the entire network transaction history.
Now, Assumeutxo is able to bypass that requirement of storing the entire Bitcoin accounting or blockchain. It does this using serialized UTXOs captured in a “snapshot” at a given point in time. UTXO serialization includes metadata such as the number of coins contained in the snapshot and the header of the last block encapsulated in the snapshot (its "base"), among other data.
Assumeutxo is O'Beirne's idea, but it also included interventions by Mike Schmidt and review by other developers such as David Harding and those identified as Sjors and AJ. From a technical point of view, Assumeutxo is described as follows:
It is a chunk of data embedded in the source code that is committed to the hash of a serialized set of UTXOs that are considered valid for some height of the string. The final format of this commit is still subject to debate because generating it is computationally expensive, and its structure affects how we store and transmit the serialized set of UTXOs to and from other peers. But right now, it's simply a SHA256-based hash of the contents of the UTXO array generated by the existing GetUTXOStats() utility.
Assumeutxo has already been added to the main Bitcoin repository, but is not yet active in the protocol. Progress is being made with testing on networks such as regtest, testnet, and signet, O'Bierne explained. After waiting a while, the few lines necessary for its implementation in the main network will be changed, he explained.
The main benefit of Assumeutxo is that it makes the process of starting a Bitcoin node running easier and faster. “Right now, the initial download of blocks is a process that increases linearly with the size of the chain's history,” explains the repository of this development.
It is added that the process of downloading and installing bitcoind can take "from four hours to several days", depending on the hardware and network bandwidth. This “discourages users from running full nodes, and instead incentivizes them to turn to clients with a reduced security model.”