the website is : online-reminder.net

does anyone have any suggestions as to why some of the images are loading slowly (they are loading about a second after the other content, i would like everything to load together - i am not talking about the google ads) ? None of them are large image files so that's not the problem. This problem is evident on all the pages on the website.
Also, any general suggestions as to how i can increase general load speed on the website or any general thoughts for improvement.

Many thanks for your help