The role of a peer's feefilter in estimating their pool size is examined, albeit with limitations due to privacy concerns and calculation methods. Factors affecting the feefilter include its half-life calculation, memory usage variances by different mempool maps, and intentional rounding for privacy. These elements underscore the complexities in managing network interactions and optimizing transaction processing and block reconstruction in blockchain networks.

An analysis on compact block reconstructions showcases a critical distinction between low-bandwidth and high-bandwidth modes in terms of performance and operation. High-bandwidth mode, responsible for approximately 75% of compact block deliveries, sends a cmpctblock message prior to block validation. In contrast, low-bandwidth mode involves an inv/headers message and a subsequent getdata(compactblock) request from the receiver. Observations indicate that high-bandwidth mode leads to fewer transaction requests during block reconstruction, suggesting higher efficiency. Most compact blocks are delivered with only the coinbase transaction pre-filled, pointing to potential optimization opportunities in low-bandwidth mode by pre-filling unknown transactions to reduce the need for further requests. However, such optimizations have not been implemented in Bitcoin Core as indicated by a TODO in the codebase. The impending release of Bitcoin Core v28.0, introducing full-RBF by default, presents an opportunity to revisit these operational modes and possibly improve low-bandwidth compact block delivery and reconstruction efficiency.

Further insights into compact block reconstruction are garnered through the debug=cmpctblock logging feature on monitoring nodes, focusing on the efficiency of block reconstructions within the Bitcoin network. This study examines the frequency of additional transaction request rounds (getblocktxn -> blocktxn) necessitated by a node's lack of certain transactions during the reconstruction phase. Despite minor configuration differences, most nodes adhere to Bitcoin Core's defaults, but adjustments such as increasing maximum connections or changing policy settings (like mempoolfullrbf=1) significantly affect the block reconstruction process. Periods of heightened mempool activity correlate with decreased rates of compact block reconstructions not requiring additional transaction requests, highlighting network congestion's impact on reconstruction efficiency. Notably, changes like enabling mempoolfullrbf by default could expedite block propagation times, suggesting policy deviations could enhance overall network efficiency. The investigation also uncovers disparities in median block reconstruction duration based on the necessity of additional transaction requests, emphasizing the influence of node connectivity and hardware capabilities on reconstruction times. The exploration raises questions about the need for extra transactions in different bandwidth modes, the effects of varying extra pool sizes on efficiency, and the performance evolution of block reconstructions, especially with the adoption of full-RBF by miners. Comparing outbound-only nodes to those accepting inbound connections might offer further insights into optimizing block reconstruction processes across the Bitcoin network.