Speed is determined by Internet not by the site unless the links are broken in which case speed wouldn't matter since they're broken anyways ;P
The sites I use most are watchanimeon.com - because it has the most shows and almost all of the ones I watch. Only bad thing is the links are user provided and not really monitored so some might be broken and the quality differs from link to link.
For dubs I use watchcartoononline.com - Same as above ^
