Paulo Sousa optimized HyperLogLog operations in the redis/redis repository, focusing on accelerating PFCOUNT and PFMERGE commands for large-scale cardinality estimation. He applied low-level C programming techniques, introducing branchless comparisons and leveraging ARM NEON SIMD vectorization to enhance performance on both AArch64 and AMD64 architectures. Throughout the process, Paulo maintained strict behavioral compatibility, ensuring that the optimizations did not alter existing functionality. His work targeted reduced latency and improved throughput for real-time analytics and caching workloads, demonstrating depth in performance optimization and cross-architecture engineering. The project showcased expertise in ARM NEON, SIMD, and low-level systems programming.