If you're having problems with Safari 8.0 hanging on some web sites read on.
I was having some problems with Safari 8.0 on Yosemite, some web sites did not completely download, the progress bar stopped before halfway. It was variable as trying again sometimes worked. On Apple discussion someone suggested changing in the system preferences > Network > advanced > configure IPv6: to Link-local only and apply, then do a restart.
This has seemed to work, been using Safari throughout the day without the stalling problems.