I do not believe it is a Windows issue. It may be related to this Known Issue in the SDK's release notes:
"The Viewer and the visual examples CPU utilization is high, when streaming depth or color (DSO-7888)"
This issue is no longer listed in the release notes for the newest SDK version, 2.10.4, so you could try installing that if you have not done so already to see if you get better performance.
Your firmware is also quite out of date. It can be updated in Windows with the firmware updater tool.
And this is the download page for the latest firmware file, 5.9.9, which has just been released and is compatible with the latest SDK version.