Optimistic mining tip (slow block propagation)

The optimization of block propagation and validation times is crucial in the cryptocurrency domain, particularly in ensuring that potentially invalid jobs are only sent to hashers for minimal periods. This optimization encompasses various strategies aimed at enhancing the efficiency of these processes in both standard operation and attack scenarios. One significant area of focus is the reduction of relay-filtering, which, although intended to minimize the chance of a transaction being mined by denying its relay, contradicts the goal of fast propagation of consensus-valid transactions. This issue has sparked considerable debate within the community.

Recent proposals have introduced next-block-template synchronizations as a potential solution to improve block propagation times significantly. Additionally, enhancements in block validation speed, UTXO and mempool state update, and template creation have been identified as critical areas for improvement, with the employment of Cluster mempool technology presenting a promising avenue for further exploration.

It is noteworthy that only a small fraction of bitcoin nodes engage in mining activities, such as generating block templates utilized by miners, and thus have a direct incentive to reduce block propagation times. These nodes can adopt measures like establishing good peering connections, maintaining large mempools, and avoiding filtering to achieve this objective. However, since most nodes do not participate in mining, they are generally less affected by block delays, except in cases where the node generates a high volume of transactions. Nevertheless, the global propagation of transactions relies on the cooperative efforts of the entire network, including non-mining nodes.

The shift towards more miner-generated templates, as opposed to those created by pools, has been discussed as a means to decrease mining centralization. However, this approach could inadvertently slow down block propagation times due to the increased size and diversity of the block creator nodes set. Despite this challenge, the adoption of Stratum V2 and the ongoing practice of using custom templates for mining blocks, as seen with Most Ocean mined blocks, highlight the community's commitment to addressing these concerns. For further details on the consensus cleanup effort, see BIP 54.