Almost all of our themes support the infinite scroll plugin that enables you to scroll down limitlessly within your blog. This plugin is very convenient. However, it may consume a lot of memory, making your browser freezes sometime. This is why we made your images render less heavy, which may cause your images pixelated.
You can still, however, make it render in as high resolution as possible. There's a option on the customize page. 'Use high resolution images'. You may turn on this option. Be aware that this may consume much memory on your computer.