Personally, I haven't had any issues with myspace, nor have any of my other friends, so I can't say much about it. I'm almost positive on the facebook problem because I've been searching forums since it started and I've tried everything they've had to offer and then some with no success. After hearing about all the friends I have with the same issue, it can't be coincidental. Something has to be wrong with these sites. If you've also been through several forums explaining about dns flushing, clearing your cache, cookies, malware removal, etc. and have had no success with either site, it may be safe to assume it's at least a similar issue with myspace too.
The only thing I've been able to do as a "band-aid" until hopefully they fix it is to disable my firewall while I'm visiting facebook. It still takes forever to load, but it usually responds after several minutes (think dial up speed). It might work for myspace too, but use that method at your own risk. I'm still searching for solutions I haven't heard of or tried yet >_>