Done! Resized with Photoshop. (From 4MB Total to 1MB for 3 bg images).You should optimize your hompage image because it is huge. Load time is large because it takes time to download that large file.
You could easily do it here: https://kraken.io or using Photoshop. There may be other optimizers, like Caesium or PNGgaunlet (both for windows). Heck, I believe that if you submit your website for Google Pagespeed they will give you a zip file with all your website images optimized.
A good size is anything lower than 500KB.
Keep it up!