Fractal Bitcoin has addressed user concerns regarding incomplete block filling on its mainnet, as reported by Odaily. The company announced on the X platform that it is currently investigating this issue, which stems from miners’ tendencies to prioritize high-fee transactions and the constraints imposed by two block size limits: the maximum block size in bytes and the maximum number of SIG operations.

The challenge arises particularly with high-fee MULTISIG transactions. When a block approaches the 80,000 SIG limit, it can no longer accommodate additional transactions. In theory, SegWit transactions only consume 1 SIG, potentially allowing for up to 80,000 transactions in a block. However, this scenario is rarely achieved in practice. In contrast, MULTISIG transactions require 84 SIGs each, significantly reducing the maximum number of transactions that can fit in a block to just 952. This discrepancy leads to blocks being underfilled in terms of their byte capacity.

Fractal Bitcoin pointed out that some blocks may appear completely filled due to the inclusion of low-fee, non-MULTISIG transactions, which can occupy up to 75% of the available block space and raise total block fees by around 20%. The company clarified that these dynamics are inherent to the existing Bitcoin mainnet architecture and are not a flaw in the Fractal browser itself. They reassured users that they are committed to closely monitoring the situation and enhancing network connectivity and performance moving forward.