I can totally feel the OP's pain. Safari fails to render 1 out of 10 Pages correctly. Thats an issue with the retina MacBook Pro, but it's there since the thing is on sale.

Sometimes, out of nowhere, my TimeCapsule Backups take forever, although they are always around the same size.

With some Access Points (non Apple), my MBP takes forever to log into their Wifi after wake from sleep.

My MacMini Server fails to serve its Desktop via VNC when no display is attached, because they use GPU accel. to render the video and the GPU Drivers does not get loaded when no Display is attached. If got a freaking VGA-Display-Fake Dongle on my Server to solve this.

iTunes, don't get me started. The last 10 movies i added to iTunes have the Cover Art Tab greyed out so that i cannot add Cover Art to them. God knows why.

iCloud.. ICLOUD!

And so on. And i'm a guy who takes its time to dig into things. I want to get my stuff solved, but sometimes you just can't.