A slow Switch microSD card can cause laggy game loads—here’s how to speed it up. First, check the card’s speed class: Switch works best with UHS-I, U3, or V30 cards (minimum 60MB/s read speed). Replace slow cards (e.g., Class 10) with faster ones from brands like SanDisk Extreme or Samsung EVO Select. Format the card to exFAT using your PC—this optimizes it for Switch. Delete unused games and files to free up space—full cards slow down read/write speeds. Avoid using the card for non-Switch files (e.g., photos, videos) as they can fragment data. Update your Switch’s system firmware to the latest version, as Nintendo releases performance fixes for storage. If the card is still slow, test it in another device—if it’s slow there too, the card is faulty and needs replacement.