Threaded jitter

I have a task in my game that updates the position of a player character and also moves a node that I use to project some textures.
This worked fine until I had a total of 3 projections (terrain texture, terain normal map, shadows and ‘fog’), adding the last projection gave a strange effect - the frameratemeter still shows 80-90 fps but it feels like 10-12fps. I’ve set my update task sort to a very low value (-51) and it got a bit better, but not exacly good.
This only happens with the threaded pipeline ( threading-model Cull/Draw in prc) and only if I add this third projection (it projects a alpha-mask-fog-texture over a few geoms under a common node).

Am I doing somethig wrong, is this a bug or that’s a threading artefact that I just have to live with? It’s a bit sad if I can’t use the threaded rendering, it gives me nice 30% framerate boost.

Any help? Any ideas? Sourcecode can be provided if it helps (a bit messy and on the fat side).

I don’t have any ideas offhand. If it were me, I’d probably investigate it by trying to produce the minimum application that demonstrates the problem.

There’s a good chance that this exercise will reveal what’s going wrong, but if it doesn’t, at least you will have a bit of sample code that’s much easier for other people to take a look at.


I can’t seam to reproduce it with a simpler setup ;(
That kind of hints it must be something I’m doing.

Here’s the code I have (+models and textures), it’s held by strings, bubble gum and duct tape in some places, but it’s a work-in-progress: