My small contribution.
I had already considered the problem of load times with an animation I'm working on (and I have suffered with other external renders at greater or lesser extent) and in the current state of animation capabilities of octane I'm in a situation similar to Roubal, so I'm still waiting for newer versions.
Also as I said in another thread, in linux you have to add more time to load their own octane.
The things I think could improve the situation greatly (at least with my animation) are the following:
-A resident mode, in which the program remains in memory, and the plugin (in my case the blender) communicates with it to pass the changes in the scene and expected to pick up the resulting image. It could be very similar to the current state, but when invoke command line octane, instead of starting the program, check if it is running, and passes the parameters.
-Instances. At least in my animation, much of the geometry is stationary objects (stage), so with the instances, there should be possible to separate stationary objects from the mobile ones, having to process between frames only moving objects (and thus pass from the plugin to octane). I've used something similar with blender and other external render and the problem of time to export more external render load almost disappears.
-Support for blender 2.5. I'm doing the animation in this version of blender that is unstable at the moment, but it will allow better integration of octane. The animation support is incompatible with 2.49, so if you load the scene with that version to try to use the current plugin, all traces of animation go away.
With these options, I estimate that in my case could move from 70 seconds of the blender export more 15 seconds of octane load more 45 second to load of the scene to 20 seconds of export more 14 seconds of octane changing the scene. In total would go from just over 2 minutes per frame to slightly more than half a minute.
I could be wrong, but I think what I present is feasible.
LiVux 64bit | Geforce GTX260 Core 216 and GTX470 | i7 860 | 8Gb | Drivers 275.09.07 | Cuda 4.0.17