A Lazada seller page is a grid of product images, and its perceived speed is almost entirely the sum of those files. Upload full-resolution phone photos and the grid crawls on mobile; compress blindly and the product looks soft exactly where a buyer is deciding whether to trust the seller. The sweet spot is a modestly sized square image compressed to a quality that still holds detail. Skwish resizes to the listing frame and compresses in your browser with a live before/after size readout, so you can stop at the first quality setting that still looks right. Batch a whole catalogue, export it in one ZIP, and never send supplier or product photos to a third-party shrinker to get the weight down.