In this study, we discover a connection between the fast-charging performance of supercapacitors and the ionic effective diffusion coefficient in the electrode nanopores. We assess the fast-charging capabilities of nanoporous carbon supercapacitors with electrochemistry experiments and employ PFG NMR to investigate the underlying mechanisms affecting their performance. We hypothesize that greater tortuosity of the pore network impedes the transport of electrolyte ions to charge storage sites. Our results reveal a positive correlation between effective long-range diffusion probing diffusion at > 3 µm lengthscales ( D ! ) and the rapid charge-discharge behavior of supercapacitors. This relationship is primarily influenced by material tortuosity. Building on previous NMR studies of supercapacitors , our work identifies pore network tortuosity as a critical factor linking electrode structure to rate performance, demonstrating how NMR can provide unique insights into the mechanisms driving supercapacitor efficiency.