Jito introduced its new tool, IBRL Explorer, on the X platform, designed to improve the observability of the Solana block building process. Jito stated that during block data analysis, the team discovered that some validators exhibit "late packing," where transactions are concentrated at the end of the slot. Jito pointed out that this behavior slows down state transitions, increases end-to-end latency, and reduces network determinism and application stability. To address this, IBRL Explorer introduces an IBRL score to quantify validator block building performance. This score is based on metrics such as slot time score, voting packing score, and non-voting packing score, with the slot time score giving higher marks to those who complete block building within a specific time threshold. Jito also stated that the tool has been used internally to identify late packing phenomena, including those occurring in multiple data centers in Tokyo, and the cascading effects of late packing of non-voting transactions. Jito also clarified that the IBRL score is calculated based on observable behavior and does not cover all factors that may affect slot time and transaction distribution; the results may also be affected by variables such as infrastructure and network conditions.