To speed up 3D models with textures, optimize resolution, format, and organization to reduce memory usage and processing strain. Use compressed formats (e.g., DXT, BCn) instead of uncompressed PNGs/JPEGs—they keep quality acceptable while cutting GPU load. Resize textures to match the model’s visible size (a small button doesn’t need 4K). Combine multiple textures into an atlas to lower draw calls, which speeds up real-time rendering.
For a simple next step, try compressing one texture with a free tool like GIMP (use its "Save as DDS" plugin) and test performance—this shows impact without overcomplicating things.