Hello! From a page speed, SEO and usability standpoint - is there any real difference between: http://example.com/images/image.png vs /images/image.png I get it, while the former is quicker and easier to write. However, with Wordpress - would it be worth my time to go in and remove the domain across the board, leaving only the directory path? Does one provide an advantage over the other? Thanks for all of your insight!
For page-speed purposes, and/or SEO, it shouldn't matter. However, if you consider portability, hardcoded full URLs is bad. At least, if you're gonna use full URLs, you need some sort of pulling of the current domain, so that you can port it to whatever domain you're using. Also, the problem of http vs https - relative urls doesn't care about what protocol you're using, and generally the relative urls are a better option overall.
That would be my vote. Having the actual images relative /images/x.jpg but the actual URLs absolute: http://google.com/images/x.jpg via a configurable param. This will make it easy to switch your assets to CDN if you ever need to. That can easily be solved by using protocol-less urls: //google.com/images/x.jpg IMO relative urls storage wise, but when serving have the absolute urls (unless you know you will never need it).