Hello and Welcome!
This is a simple fix
You’re slowing things down. The first .jpg in your slider is 1.24mb and the second is 2.96mb.
Use something like Imageoptimizer.net (a free compression tool)
Leave the max width/height at the default settings on imageoptimizer.net, upload your image and compress it.
Replace your current images with the compressed images. This should fix your issue. Also, make sure whatever is in the background of your slider (showing up before your images load) is removed unless it’s necessary.
Make sure any images/video you upload to your site are optimized and compressed. For background videos, I like to use clipchamp.com
This should speed everything up for you