ConnectivityTracer.cxx in the raytracing library is one of the files that takes more time to compile than most others. To speed up compiles (in particular, parallel builds), split ConnectivityTracer.cxx into several smaller files that compile particular instances of worklets at a time. This will hopefully avoid memory issues with compilers as well as divide the compile time more evenly across processes.
The implementation uses the instantiation feature of the VTK-m CMake scripts.