For associated stories see the blog entries for
September 14, and
September 4
The bug first appeared after the 31st August update for Windows 10 Anniversary edition. However Microsoft said the problem was due to code inside the NVIDIA and AMD drivers.
Early reports say that the frame rate issue may have been resolved, at least for NVIDIA graphics users thanks to a driver update released today from NVIDIA,
version 373.06
Of course it is too early to say for sure, so please keep and eye on the Linden Lab Jira
BUG-37795
Update
Overnight many more people have indicated that this issue has finally been resolved and AMD have now also released a new driver to fix this problem. AMD 16.10.1. So if you have been suffering the frame rate issue, updating your graphics drivers to the latest release would seem to be the solution.