What device are you using to see it? This is what i get while opening your site from Samsung s6, screenshot. The slider is scaled down to mobile size but the images show up one by one just as they should.
Let us know.
You could add a javascript snipped code into General Options > Custom JS Code, which lets slider show only after entire page has been loaded.
Sorry but this is a customization not included in support. You could do this yourself or hire a developer to do it for you.
