Oh man, dealing with massive image payloads is the absolute bane of portfolio design! You are completely right to steer clear of unverified cloud converters—uploading unreleased commercial or personal art to random external servers is a major security risk. What completely saved my workflow and brought my mobile loading speeds down to a fraction of a second is using https://compressfile.pro/compress-jpeg/ The absolute killer feature of this tool is that everything runs 100% on the client side using modern browser capabilities, meaning your files never actually leave your local storage or get uploaded anywhere. You just drag your heavy art folders in, let it optimize instantly, and pull down crystal-clear files that look identical to the original!