i haven’t seen any problems with cs3 (mac) and multiprocessing since the 8.0.2 update.
since you are using rsmb, i assume you have it applied to footage layers… try pre-composing those layers and pre-rendering them.
also, there are effects that will disable multiprocessing in ae (i’m not sure how nucleo handles those)… but particle playground, the cc time effect (widetime, time blend) and the auto-color correcting effects (auto-levels, auto-curves, etc) are some of the bundled effects that will disable multiprocessing. not sure if something like that may be effecting your render…
one other thing… when you say half-res render, do you mean a render from the render queue, or a ram preview at half-res. if it is a half-res ram preview, the preview may render faster due to preview settings that are disabled, like motion blur and frame blending… for the render, by default, those would be enabled and that could cause a significant increase in render time vs preview rendering. if opengl is enable for previews, this too might lead to faster previewing.
lastly, if disk caching is enabled, you can get a performance hit if the disk cache is on the same drive bus as your media and renders are set to… when you are rendering at half res, each rendered frame and cached frame is 1/4 the size as the full frame, and if they are going to the same drive (or drive bus) this could be creating a data bottleneck, resulting in slower performance.
you should be able to test this by running the activity monitor (mac) or task manager (windows) during the render. check to see what the background processes that nucleo is running are doing (or if you use cs3’s mp, check ae’s. if the cpu numbers aren’t getting above 50% or so, then it’s likely that you have a data bottleneck.
KCPQ, KMYQ & KRCW