watching streams on a website are choppy in fullscreen on google chrome.

I'm going to need a lot more data:

https://forums.adobe.com/thread/1195540

I'd start by working through the video troubleshooting guide.  In particular, make sure you have the latest available drivers updated for your hardware.

https://helpx.adobe.com/flash-player/kb/video-playback-issues.html

If you're still stuck, please follow the directions in the guide on providing the dxdiag report and additional information about what you tested and saw.