Vray 2.20 super slow when the max FB is open

[^Lele^]

As the title says.
The slowdown is randomic, but HUMONGOUS (10-100X).
Think of RTT: both the vray FB and the max ones come up, and the moment i close the max FB Vray picks up speed.
Rendering within the max FB is just slowness(tm) guaranteed.

It may have been fixed already, or not be a Vray issue, but i thought i'd flag it.

[vlado]

Do you have the 3ds Max bitmap pager enabled? Do you have the light cache "show calc phase" option enabled too?

Best regards,
Vlado

[^Lele^]

neither, nor.

[vlado]

Then I have no idea Is this on any scene?

Best regards,
Vlado

[^Lele^]

Actually, no.
I was doing some performance profiling for a noise analyser script (yeah, i'm still on that one...), and out of laziness i was using the max FB, getting the oddities in performance with a plane and a domelight.
Given i have a 24 cores beast, with the latest and greatest of Intel's chipsets, i thought it may have been an issue with memory mapping (non-SMP), and god knows what else...
Changed every possible relevant bios setting without results, i even got a different workstation, which seemed to work at the IT desk.
It got back to me, and again it was slow and erratic.
The moment i used the vray FB it all stopped misbehaving.
Rendering to texture opens a max FB by default, even if the vray Fb is active, and that's when i noticed that the slowdown (which is, incidentally, growing the more vray renders: it starts at normal speeds and slows down more and more as the render progresses) would disappear the moment i closed the max FB.
It could really be down to an odd hardware combination, but i'd have to confirm this (i'll grab someone's older workstation tomorrow).