The options on this page are relevant to Render Styles. See Creating a Rendered View
Transparency Shadow: Specifies whether a render created with a render style will support shadows cast by transparent objects.
Multi Threading Options
Enable: Enables multithreading for rendering via the use of multiple CPU cores.
Use Automatic Number of Threads: If On the number of threads will be automatically determined.
Threads: specifies the number of threads to use if "Use Automatic Number of Threads" is turned off.