Have you ever visited a website and found it really sluggish to use? Ofcourse you have. But chances are the images weren’t optimised and this drives me nuts. I see this happening all too often with web designers. We need to pay attention to performance on mobile devices and tablets, and a website over 4mb in size needs drastically optimising, if not for the user, then for Google. There’s a good chance that your website will hit a penalty with Google’s constant algorithm updates.
Image sizes (unless you plan on using a large 2000px wallpaper or wide banner on the site) needn’t be larger than 1000 pixels in width. These in turn can be compressed to 90% without flossy quality becoming and issue.
As for logos and PNG’s, avoid compressing where possible. But if you must (and I mean absolutely must compress PNG images) use TinyPNG.
Compressing images isn’t just necessary for keeping traffic data quota down, but it’s important for user experience.
Resizing images needn’t be a problem too, use RIOT tool to compress and resize images. If you’re using wordpress try the Resize image after upload plugin. Pay attention to quality, sometimes main design elements look far better uncompressed, but just keep the maximum size of your website at 4mb. That’s the maximum size current technology can comfortably work with, without lag, or penalties on Google SERP’s for having a slow website.