This patch will reduce the number of times that we need to
recompile the kernels. It does this by enabling selected features
by default. So when the user needs them that the kernels are
already available.
Other features are enabled by default for background and foreground
rendering. When in background rendering the user wants the best
render performance. When in foreground rendering the user wants
the least amount of recompilations.
Enabling volumetrics or subdivision evaluation will still trigger
a recompilation during foreground rendering.
See attachment for detailed information about the kernel
recompilations