What lossless image format saves faster than PNG in IrfanView?

For a straightforward lossless workflow, TIFF is worth testing in IrfanView. It’s commonly used for edited images and may save more conveniently than PNG, although it can also produce fairly large files. The best choice is to test TIFF, lossless WebP, and PNG on a representative photo and compare both save time and file size.

If these photos started as JPEGs, converting them to PNG won’t restore any detail that was already lost, and the resulting files can become dramatically larger. PNG does make sense if you need to preserve the current pixels while adding annotations, but consider keeping the original JPEGs untouched and saving the annotated versions separately.

Your hardware is already more than fast enough, so PNG encoding itself is probably the limiting factor rather than the SSD. You could try TIFF or lossless WebP if your IrfanView setup supports them, but the speed and file-size difference will depend on the image and compression settings.