WordPress + BlockUI or a splash page [closed]

Images that are 350×235 shouldn’t load slowly. I would recommend trying to speed up your site before looking into adding custom code or a loading screen. A plugin like EWWW Image Optimizer will optimize your images in a lossless compression (no degradation of image quality) and a cache plugin will help with compressing pages to get them to load faster. Here is a good review of the best caching plugins, you can choose based on your budget, several are free.