Cycles: fast but peppered with occasional slow render frames

I’m finding that if I use Cycles to render an animation, while it gives me frame renders of about 10 seconds, there are also occasional frames which take a whole 5 minutes. Is there a way I can figure out what’s going on and optimise my hardware?

Operating System: Ubuntu
Graphics card Evga GeForce GTX580

I assume you doing GPU rendering…right?
On windows there is GPU-Z so you can watch what your GPU is going through while it is rendering. Perhaps some kind of memory fragmentation is occurring and causing a slow down on certain frames till it gets cleared up. Just guessing…

GPU-Z For Ubuntu:

My Ubuntu was unable to locate sensors-applet, though given it was 2009 those posts were made, it may have been dropped. I have psensor which doen’t give CPU but does show HD and GPU… yes the GPU goes up while rendering though I’m not sure what I can do with this information; it’s expected.

I think you are right that for whatever reason Blender is giving various frames to CPU. Perhaps it’s asking the GPU which refuses because it only just had a few and then reverts? I don’t see any option in Blender to insist that GPU should be used every frame (and wait until available) though when CPU takes 5 min for what GPU does in 10 seconds… it would make a lot of sense.

Would speed up my work immensely to get to the bottom of this.

Currently booted into Windows 7 and am rendering the same file. Not seeing the problem yet. Interesting.

Maybe Windows is better than Linux at Cycles in animation context?