Hi,
Does GPU speed exponentially drop as number of threads increase beyond a certain number?. I used to allocate number of threads= number of transactions in data under consideration.
For Tesla K80 I see exponential drop in speed above 30290 Threads. 
If true, is it a best practice to keep number of threads low and iterate over the data to get results at optimum speed. 
How to find best number of threads for a GPU?

Thanks
Aseem