I also have this problem. Started about a week ago.
Safari randomly can't load pages and images.
Tried unplugging and replugging my wireless router.
Tried 32-bit mode for Safari. Tried resetting Safari which helps temporarily.
Have no plug-in's or add-on's.
Tried everything else listed on this discussion.
Guys hi! I have noticed...even on 10.8.3 that if the web pages come to a screeching hault it can be fixed untill the next time by turning off the airport at the top right hand of the screen and then turn it right back on...even without restaring safari it starts working again when i refresh the page after. I have noticed the web pages stop loading if i stop using my computer for 10 minutes or so. But it has happened even while surfing...so just a few things I wanted to point out. I hope this helps somebody.
I tried OpenDNS, disabling prefetch, empying caches, disabling caches, turning on/off extensions, turning on/off plugins, and so on. None of those work for long.
It's a shame because I really want to use Safari. But this is a problem that has been going on for years now.
Either Apple isn't aware of this problem, which is hard to believe, or they can't fix it, which is hard to believe.
My only choice is to use another browser, which means that I can't use iCloud Keychain.
Was really hoping Mavericks would fix this problem, but alas...
Late-2012 rMBP "13, OS X Mavericks, Safari 7.0 (9537.71)
FWIW, I tried a lot of different things! I was starting to get worried I was going to change some obscure setting I didn't totally understand and warp my system for good!
I fixed it with a very simple 2 step process;
1. Reset router
2. Turn Wi-Fi off and back on again.
This was the order I took. On re-evaluating it, it may be better to turn off the wifi, then reset the router. After the router has re-cycled, then turn wifi back on. It was simple; but it worked! Good luck.