Troubleshooting WDS Multicast performance issue.
If the multicasting is very slow, you can check the following two settings to see which impacts the performance:
1. Network Profile on the Network Settings tab of the WDS server properties. However, this relates to the physical network adapters and cables.
2. The lowest client machine.
If you have more than one client machines joined in the multicast session, and if these machines have different hardware configurations, the speed will be impacted by the slowest one. You can take a look at the following article for more detailed information on this:
If these methods don't change the performance, and if you think the speed is really very slow, you can test several client computers on your network, and compare the performance with the test results outlined in the "Performance and Scalability Expectations" section in the following article:
Please note that the test results may vary on different hardware devices and settings (both on server and client machines).
Besides, here is another article just for your reference:
Analyzing Performance Problems: