I didn't mean to sound defensive, just trying to explain how things work so it's easier to know how to approach your problems.
We always recommend leaving the subdiv cache at its default setting unless there is a really good and *specific* reason to do otherwise. In fact we're contemplating just removing that setting entirely as it seems to cause more harm than good (e.g. memory issues from people making it big because they think it will make renders faster). As for threads, set it to as many threads as your CPU can accommodate, or that -1 if you want to maintain a bit more responsiveness from your system while rendering (this is what I do). In my case I have a Core i7 CPU with 4 physical cores, but it also has hyperthreading, so up to 8 threads can be advantageous, and I have mine set to 7. Just keep in mind that efficiency goes down with more threads, so you have access to more compute resources, which is good, but there's no point in assigning more threads than you have cores. Generally it's best left at default.
I consider 8GB of RAM to be a decent amount for working with TG. 16GB is really more optimal, to be honest, but 8 is fine. IF you're running into memory constraints with what you have now (4? 6?), then adding more RAM could help, but it's generally not going to improve performance so much as it will let you create and successfully render more complex scenes and higher resolutions.
I think setting atmosphere to 64 samples as a matter of policy is really unnecessary. Clouds now use a "Quality" setting which should remain around 1 unless you have very good reason to do otherwise. Avoiding excessively high settings in those two areas alone could save you a lot of render time. The default of 16 atmo samples works fine in an average daylight scene. With higher haze, lots of shadows, or near sunset increasing to 24 or 36 may be necessary; occasionally 64 is needed to really remove all grain from the atmosphere. But it's also important to get a good sense of where noise is coming from in your sky. It can be due to both sky and atmosphere, and sometimes increasing samples for one will not fix the problem. Increasing both as a matter of policy just to handle what may be solved by increasing only one is clearly not very efficient, so it is worthwhile to experiment a bit and get a good sense of this.
Basically the message is this: the defaults are set that way for a reason and they work pretty well. Yes, you can increase Detail for better terrain and sky quality (though don't go above 0.75 unless you are sure it will benefit you, and even then only for final renders); yes, you can increase antialiasing for smoother rendering of 3D models, especially vegetation, and using values of 8 or 12 with a plant-heavy scene is reasonable. Just don't get into the habit of increasing settings from the start and regardless of the content of the scene. Get to know when 8 or higher AA is actually necessary and *only* use settings that high when you need it. etc.
- Oshyan
