@MartinSK

I try to compare IPR algorythm to BUCKET algorythm ...

I do not know if you've noticed but from my tests, for IPR algorithm there is no anti-aliasing applied. As for multipass algorithm there seems to be a pre-defined anti-aliasing.

I know that my experiment is not about indirect light ...

If you still have the same problem , you could send me your file so that I take a look.