System: Houdini 21.0.478
Renderer: Karma XPU
Hardware: Windows 11, RTX 4090

Every time I hit render in Karma, I need to wait ~15–20 seconds of black screen
before seeing the first pixel. Even a simple asset like a single SpeedTree tree
takes "forever" to initialize. Pre-compiling kernels helps a bit, but the startup
is still painfully slow compared to other renderers.

In Octane or Redshift, the same SpeedTree renders almost instantly — first pixel
shows up in a second or two. Karma, on the other hand, makes me feel like I'm back
in 2000 waiting for renders to boot up.


I understand Karma is built on USD/Hydra, and that's great for pipeline use.
But Pixar's own pace with RenderMan and Hydra is extremely slow (some might say
"too zen" 🧘). Please, SideFX, don’t follow that example — artists need a snappy,
modern rendering experience for lookdev and daily work.


Please optimize Karma's startup speed, especially the Hydra → Karma sync stage
and texture/material initialization. Solaris is powerful, but without faster
interactive feedback, it's hard to use Karma over Octane/RS for real projects.

Right now Karma feels like a great renderer trapped behind a very slow door.
Please make that door open faster!

Sounds like a tesselation issue.

Have you tried to turn off catmulclark on the mesh or reduce the dicing quality?

If I remember correctly Redshift will only tesselate with a minimum edge length of 4 pixels by default.

Karma is around edge length of 1 pixel by default?

So by default Redshift should be faster, as less tesselation is happening.

EP nineteenma
Every time I hit render in Karma, I need to wait ~15–20 seconds of black screen
before seeing the first pixel.

This is via MPlay? Or does this happen in IPR (ie the viewport) too?
If only with MPlay try setting this envvar and let us know if the stall still happens.

KARMA_XPU_OPTIX_FAST_COMPILE_OVERRIDE=1

(please note the use of this envvar may reduce performance a little in mplay)