I’m not sure about galleries versus repeaters loading time without testing. What I would target next is image/gallery optimization. For example, if you are loading full/large images on the home page when you really only need a small/thumbnail size you could load small images on the home page and only the full when someone clicks into the single product.
Also with your galleries, are you loading images from multiple galleries per page or are all the homepage images in the same gallery on load? Articles for Wix galleries do recommend loading only one gallery per page .
You can also use a load more button to limit the amount of gallery items loaded at one time. Gallery optimization articles in Wix also recommend loading galleries “below the fold” if possible to increase speed.