The performance of semi-autogenous grinding (SAG) mills is strongly influenced by liner design, which must enable rapid start-up while delivering sustained durability under high-demand operating conditions. Conventional steel liners, while proven in durability, impose limitations due to their heavier weight, resulting in elevated mechanical stress on mill components and constrained rampup strategies. These factors often lead to delayed achievement of target throughput and reduced operational flexibility. This paper evaluates the impact of converting from all-steel to hybrid liners on 36-ft-diameter SAG mills at two mine sites, one in Chile and one in Australia, focusing on start-up behaviour, mechanical response, and long-term production outcomes. Hybrid liners offer a reduced weight profile and a simplified installation process, which collectively lower structural stress on the mill and support higher mill speeds earlier in the commissioning phase. This enables a faster, more controlled ramp-up to full capacity without compromising safety or reliability. Operational monitoring confirmed that hybrid liners facilitated improved charge motion, reduced shell impact, and enhanced grinding efficiency. Mechanical monitoring indicated lower vibration levels and reduced stress on critical components such as bearings and drive systems. Additionally, hybrid liners demonstrated increased wear life and reduced downtime due to faster change-outs, contributing to improved mill availability and decreased maintenance demands. The findings highlight the potential of hybrid liners as a next-generation solution for large SAG mills. By supporting both early ramp-up performance and sustained high-throughput operation, hybrid liners offer a durable, adaptable alternative to traditional steel configurations in modern demanding grinding environments.