Adaptivity - rendering becomes very slow after reaching the limit

[Dom74]

Hello.
I'm not sure it's a bug, I'm rendering a scene with PT+HD and using adaptivity, but when the "recalculate every" pass is reached, rendering speed slow down significantly.
For example, adaptivity is set to 15 and "recalculate every" to 200, every pass is rendered in 2 or 3 seconds, until 200 passes are computed, after that, each pass take more time, about 7 or 8 seconds.
I have tried with "recalculate every" set to 50 or 100, and obtained same result.
Also, I'm not certain to understand well the adaptivity parameters, can you explain me how it works ?
thanks.

[Ondra]

yes, this is a feature, because after every "recalculate every" passes the adaptive supersampling is updated. Each pass then takes longer, but produces better results. What you want to try is setting recalculate every to about 5-10 and adaptivity to about 5. But it is still not working well

[Dom74]

Ok, thanks,
I will make some more experiments.

[xt13r]

sorry for interrupting, what is adaptivity? and recalculate every? i see them in a new corona release and found it in corona documentation, but there is no description.

[Ondra]

it is an adaptivity attempt that is currently not working very well