Thanks. I have tried your suggestion and I think it looks a little better.
I am still having poor quality when rendering in 3D. This happens whatever format I save in e.g. JPG, TIFF, PNG.
I will try to upload an example when I get home. I tried last night but the image was too big.
You should post your 3D problem as a separate post. So start a new topic and post your screenshot there. Include your OS version, Photoshop version, CPU/ram as well as your graphics card model and video ram.
3D is a function of your Graphics card. You should visit the website of your card maker, and check for driver updates for your particular card model and install them.
Another suggestion is to check your graphics card settings under Preferences > Performance > Graphics Processor Settings > Advanced. Look at Anti-alias Guides and Paths/OpenCL and see if checking or unchecking them makes a differences.
Try Basic, Normal, and Advanced.
Other than that I do not use 3D and someone else in these forums should be able to help you on this.