1. First off 200 subdivs in light cache is not enough. The bigger resolution of the image is, the higher value should be here.
Sample size also should be smaller.
2. Increase dynamic memory limit, unless you really have only 400 MB of memory
3. Noise threshold can't be 0. It can cause even wrong calculation, not mention about waste of time.
4. Don't use antialiasing filter since it doesn't do anything that you can't do in Photoshop better. These filters only restrain possibility of post-editing.
5. Use gamma 2.2