For Switch users (especially those utilizing custom firmware or emulators like Ryujinx and Yuzu), the format is the gold standard. Unlike the older XCI format (which is a dump of a cartridge), NSP is essentially a digital install identical to what you would download from the Nintendo eShop.
Digital NSP files stored on a high-speed UHS-I MicroSD card generally boast faster load times compared to physical cartridges. mario kart 8 deluxe switch nsp update dlc better