Faster indexing in `MicroXS` object (#2702) #3

Job	Run time
Python 3.10 (omp=n, mpi=n, dagmc=n, ncrystal=n, libmesh=n, event=n vectfit=n)	1h 28m 48s
Python 3.10 (omp=y, mpi=n, dagmc=n, ncrystal=n, libmesh=n, event=n vectfit=n)	2h 50m 23s
Python 3.10 (omp=n, mpi=y, dagmc=n, ncrystal=n, libmesh=n, event=n vectfit=n)	53m 52s
Python 3.10 (omp=y, mpi=y, dagmc=n, ncrystal=n, libmesh=n, event=n vectfit=n)	2h 7m 34s
Python 3.7 (omp=n, mpi=n, dagmc=, ncrystal=, libmesh=, event= vectfit=)	1h 6m 54s
Python 3.8 (omp=n, mpi=n, dagmc=, ncrystal=, libmesh=, event= vectfit=)	1h 0m 49s
Python 3.9 (omp=n, mpi=n, dagmc=, ncrystal=, libmesh=, event= vectfit=)	1h 3m 7s
Python 3.11 (omp=n, mpi=n, dagmc=, ncrystal=, libmesh=, event= vectfit=)	1h 24m 41s
Python 3.10 (omp=y, mpi=y, dagmc=y, ncrystal=, libmesh=, event= vectfit=)	3h 12m 36s
Python 3.10 (omp=n, mpi=n, dagmc=, ncrystal=y, libmesh=, event= vectfit=)	1h 5m 12s
Python 3.10 (omp=y, mpi=y, dagmc=, ncrystal=, libmesh=y, event= vectfit=)	2h 20m 32s
Python 3.10 (omp=y, mpi=n, dagmc=, ncrystal=, libmesh=y, event= vectfit=)	2h 32m 47s
Python 3.10 (omp=y, mpi=n, dagmc=, ncrystal=, libmesh=, event=y vectfit=)	2h 39m 30s
Python 3.10 (omp=n, mpi=y, dagmc=, ncrystal=, libmesh=, event= vectfit=y)	56m 1s
finish	5s
	1d 0h 42m 51s

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