Open Radar

 
Summary:
When using ScreenSharing or Remote Desktop to control/observe a remote Mac the picture is always extremely blurry to the point of illegibility making this hard to use, extremely slow or even impossible to use.

Steps to Reproduce:
Connect to any Mac running Yosmite with ScreenSharing or Remote Desktop running on Yosemite.
It's enough that Yosemite is running on the controlling machine for the picture to be illegible due to sever compression artifacts.

Expected Results:
Picture should be crisp and readable.

Actual Results:
Even when connected via Gbit Ethernet picture is blurry and full of compression block artifacts.

Regression:
This was not an issue with OS X Mavericks and any other version before. This is a new issue with Yosemite and El Capitan.

Notes:
Picture quality is so bad that it often becomes impossible to use, even when reducing color depth to greyscale or even monochrome to save bandwith. This issue is even present when both Macs are connected via wired Gbit Ethernet where I assume bandwidth to be sufficient.