Here is the blog post regarding the release of Silverlight 5, particular areas to note are the Graphics and Media sections, but there are some networking changes
Have you recompiled your application for Silverlight 5 or is this a Silverlight 4 based application with the new runtime installed? What kind of Apple hardware have you tested this on? Are you seeing the same issues on all of these computers? Have you compared this to equivalent Windows based hardware of the same class and get the same results?
Can you provide more detail on your scenario since, "more time to load" can mean many things, such as:
•Download of the Silverlight application is slow
•The application is slow and/or unresponsive
•The download of the media file is taking longer than expected
•It takes a long time for the video to be displayed after you press the play button
•The video/audio playback experience is poor, stuttering or doesn't play at all
There are also media specific questions that need to be clarified, such as: Is this audio only or video/audio? Are you doing progressive download, IIS Smooth Streaming, WMS Streaming or something else? Is this content DRM protected? What kind of video player have you created? If you use a basic SL5 application with just a MediaElement does it have the same performance problems?
It looks like there has been an emphasis on using the graphics hardware of the system which could be impacting your users. Please provide as much detail that would allow someone to try and reproduce your experience independent of your environment. If this is specific to your application or environment/hardware then it would be best to open a support incident with Microsoft to try and narrow down the issue for you.
I am going to need more information, can you answer all of my questions? You have only confirmed that you are doing progressive download, which is a request made by the browser on behalf of Silverlight's browser plug-in. Are all of your Mac computers reproducing this issue? Have you tried other browsers and get the same result?
Your applicaiton looks to be doing many things more than just video. What was the result of the test with only a 1 media element playing the video? How have you issolated the media playback from the rest of your application. What is your testing scenario and hardware?
seems to be loading it much slowly
Is it 1 second slower or 10's of seconds slower? Have you done any bandwidth profiling or performance tuning?
This is raising more questions and to effectively provide assistance more detail is needed. Please open a support case with Microsoft.
You had no other option then downgrade SL 5 to SL 4 in MACOSX.
Closing Status (ticket 112031468418757)
As per the evidences collected by the PG so far, the issue is more related the way the browsers move their data from plugin surface to screen. But this is also true that the Smooth Streaming should be degrading the stream rather than allowing the CPU consumption to get so high to let it causing an issue. So, they are perusing investigation twofold. The Program Manager of the Silverlight group has updated the bug saying they will continue to investigate the issue but it will definitely not make the GDR1. NOTE: “GDR” is Microsoft-speak for general distribution release. So, at this point we have no other option but tracking this bug after GDR1 release.
Thanks for the update. Hopefully silverlight fix this soon. People do not want to install silverlight and on top of that when content does not render, they just leave the website/product.
Meanwhile, we have decided to give preference to HTML5 version of player over silverlight. So that we show as much less silverlight to our customers.