Speed grade vs. temperature/ derating

[Altera_Forum]

Is there any information on derating for commercial products?  

 TB-090 describes it for industrial products, but I cannot find any information what the loss in speed is for increased temperature ranges. Is there any information available on what happens when the temperature goes over the specified 85C?   any help is greatly appreciated, thank you!

[Altera_Forum]

use timequest to analyse it

[Altera_Forum]

Is that reliable, even though it's not officially supported by Altera?

[Altera_Forum]

I'm not sure that Timequest has any usable models for temperatures over 85C on commercial components. It has models for the industrial versions, but they are usually at least one grade lower than the commercial FPGAs so their models can't be directly used. 

You can assume that the component will still work, but at a slower rate. Compiling the project with an increased slack may help you make the design work but there is no way to guarantee it.