Bitcoin-NG is a scalable blockchain protocol that improves upon Bitcoin's performance by reducing latency and increasing throughput without compromising security. It is based on the same trust model as Bitcoin and is robust to extreme churn. Bitcoin-NG decouples Bitcoin's blockchain operation into two planes: leader election and transaction serialization. It divides time into epochs, where each epoch has a single leader. The leader is responsible for serializing state machine transitions and generating blocks. The protocol ensures that the system can continually process transactions by making leader election forward-looking. Bitcoin-NG achieves optimal performance, with bandwidth limited only by the capacity of individual nodes and latency limited only by network propagation time. It introduces several metrics to evaluate the security and efficiency of blockchain protocols, including consensus delay, fairness, and mining power utilization. These metrics help quantify the performance of Bitcoin-like protocols and provide a foundation for comparing alternative consensus protocols. Bitcoin-NG was evaluated on a large testbed consisting of 1000 nodes, representing over 15% of the current operational Bitcoin network. The results showed that Bitcoin-NG scales optimally, with reduced latency and increased throughput compared to Bitcoin. However, Bitcoin's original protocol suffers from fairness and mining power utilization issues, leading to centralization and vulnerability to attacks. Bitcoin-NG avoids these problems by maintaining fairness and efficient mining power utilization. Bitcoin-NG introduces key blocks for leader election and microblocks for transaction serialization. Key blocks are used to choose a leader, while microblocks contain ledger entries. The protocol ensures that the system remains secure and efficient by using an incentive system that motivates miners to follow the rules. It also includes a mechanism to prevent double spending attacks by invalidating the revenue of fraudulent leaders through poison transactions. Bitcoin-NG's security analysis shows that it achieves the Nakamoto consensus under the postulate that Bitcoin does. It maintains the same security properties as Bitcoin while improving performance. The protocol is resilient to selfish mining attacks and ensures that the system remains decentralized and secure. Bitcoin-NG's performance is evaluated using metrics such as consensus delay, fairness, and mining power utilization, which show that it outperforms Bitcoin in most metrics. The paper concludes that Bitcoin-NG makes three contributions: (1) it outlines a scalable blockchain protocol that achieves significantly higher throughput and lower latency than Bitcoin while maintaining the Bitcoin trust assumptions; (2) it introduces quantitative metrics for evaluating Nakamoto consensus protocols; and (3) it quantifies, through large-scale experiments, Bitcoin-NG's robustness and scalability.Bitcoin-NG is a scalable blockchain protocol that improves upon Bitcoin's performance by reducing latency and increasing throughput without compromising security. It is based on the same trust model as Bitcoin and is robust to extreme churn. Bitcoin-NG decouples Bitcoin's blockchain operation into two planes: leader election and transaction serialization. It divides time into epochs, where each epoch has a single leader. The leader is responsible for serializing state machine transitions and generating blocks. The protocol ensures that the system can continually process transactions by making leader election forward-looking. Bitcoin-NG achieves optimal performance, with bandwidth limited only by the capacity of individual nodes and latency limited only by network propagation time. It introduces several metrics to evaluate the security and efficiency of blockchain protocols, including consensus delay, fairness, and mining power utilization. These metrics help quantify the performance of Bitcoin-like protocols and provide a foundation for comparing alternative consensus protocols. Bitcoin-NG was evaluated on a large testbed consisting of 1000 nodes, representing over 15% of the current operational Bitcoin network. The results showed that Bitcoin-NG scales optimally, with reduced latency and increased throughput compared to Bitcoin. However, Bitcoin's original protocol suffers from fairness and mining power utilization issues, leading to centralization and vulnerability to attacks. Bitcoin-NG avoids these problems by maintaining fairness and efficient mining power utilization. Bitcoin-NG introduces key blocks for leader election and microblocks for transaction serialization. Key blocks are used to choose a leader, while microblocks contain ledger entries. The protocol ensures that the system remains secure and efficient by using an incentive system that motivates miners to follow the rules. It also includes a mechanism to prevent double spending attacks by invalidating the revenue of fraudulent leaders through poison transactions. Bitcoin-NG's security analysis shows that it achieves the Nakamoto consensus under the postulate that Bitcoin does. It maintains the same security properties as Bitcoin while improving performance. The protocol is resilient to selfish mining attacks and ensures that the system remains decentralized and secure. Bitcoin-NG's performance is evaluated using metrics such as consensus delay, fairness, and mining power utilization, which show that it outperforms Bitcoin in most metrics. The paper concludes that Bitcoin-NG makes three contributions: (1) it outlines a scalable blockchain protocol that achieves significantly higher throughput and lower latency than Bitcoin while maintaining the Bitcoin trust assumptions; (2) it introduces quantitative metrics for evaluating Nakamoto consensus protocols; and (3) it quantifies, through large-scale experiments, Bitcoin-NG's robustness and scalability.