Thanks for posting in the forums! I'm sorry to hear you are experiencing issues with your PC when connecting to your Slingbox.
A Slingbox uses quite a bit more bandwidth than the Netflix or Hulu, which is why you do not have an issue with either of those, but you do with the Slingbox.
What model Slingbox is it that you have? If you have any model older than the Slingbox 350 or 500, you could try connecting to your Slingbox via the Desktop SlingPlayer. I cannot guarantee you won't have the same issue, but it wouldn't hurt to try.
Below is a link to where you can download the Desktop SlingPlayer:
Hope this helps!
The Sling Moderation Team
It's a Slingbox 500.
What encoding does the Slingbox/Slingplayer use? I can stream very high bitrate (higher than the SB) h.264, etc. from my media server on my local network to the machine and CPU usage stays low.
Via Plex in the browser or VLC or Quicktime Player, or Flash, they all don't have the same effect on the machine that the Slingplayer plugin does.
I had the same problem and was able to fix it by clicking on the settings icon and changing Quality from Auto to Better. The video degradation is negligible but the reduction in CPU usage is significant. On my recent MBP usage went from 350%, basically using all 4 cores, to <40%. Also, make sure you use the Slingplayer Desktop app, the plugins for Chrome and Safari add additional overhead that's not needed.