When I connect my tv to my laptop, a smooth stream starts buffering almost as if now too much bandwidth is being used and my fiber can't handle the increased load.  I would have thought that connecting a cable that basically just shows whatever the laptop is showing would not change the bandwidth at all, but it does.

 

Is there any reason why an HDMI cable would cause a smooth stream to start buffering?

I doubt that it has any impact on the bandwidth drawn from your fibre conection

Maybe the laptop  CPU is overloaded when trying to output at Hi resolution through the HDMI port     could be the main CPU or the graphics card CPU  could be a driver issue causing that.

I am running a workhorse machine, 512 ssd drive and 32 gigs ram with a 4 or 6 gig video card.  I can stream all day fine from the laptop, but as soon as connected to the hdmi, the stream buffers as if there's not enough bandwidth. Display on both the laptop and TV is fine when connecting the hdmi and there are no issues when connecting the hdmi and I watch a movie from the hdd on the laptop.  Only issue is streaming buffering.

Try a new HDMI cable.

 

When it comes to HDCP handshake issues the cable is the culprit 9 times out of 10.

Thanks Jai Dee.  Just bought the thing from Banana IT and they gave me 7 days to exchange, now on about day 10   It very well could be the cable as I can't put my finger on how it could be anything else.  Weird though how when having the cable connected the laptop buffers, then take it away and streaming goes back to being continuous.  

 

I've got a chromecast due to arrive in a a week, let's see how that works.

 

If this is a Windows OS machine, try opening Task Manager (Performance) tab, or Resource Monitor

 

...then watch the CPU, MEMORY or DISK statistic graphs for utilizations with the HDMI cable unplugged, or plugged in.

 

It could also be a GPU issue. Try disabling or enabling options in the software you are using to view the content.