A couple of things to consider. First, the Quick Render uses exactly the same rendering system as the normal render. The only difference is in the settings. So this should not make any difference at all *with equivalent settings*.
Second, preallocate subdiv cache is useful if you want to prevent memory-related errors from showing up late in the render. It does not *prevent* errors by any means. All it does is make any possible errors show up earlier. What is interesting is that if your scene doesn't necessarily need a large render cache, preallocating may actually make your render use *more* memory. This would probably be a rare case, and usually only happen if you are using particularly large cache sizes, but it's possible, and something to keep in mind.
I'm curious as to the details of your scene and system. Did you determine memory was an issue *before* setting the render cache so small? How many threads are you rendering with? Have you tried just 1 thread and do you get the same problems? How much memory do you actually have?
- Oshyan
