I have written a thorn MemSpeed, available at https://svn.einsteintoolkit.org/incoming/MemSpeed. This thorn is useful for performance tuning. I propose to add it to CactusUtils.
From the README:
Determine the speed of the CPU, as well as latencies and bandwidths of caches and main memory. These provides ideal, but real-world values against which the performance of other routines can be compared.