During profiling looking up topic users popped up as a hot path, this
change more than halved the amount of work it does
It reduces object allocations and method calls and avoids repeate translation
of common terms
This reduces chances of errors where consumers of strings mutate inputs
and reduces memory usage of the app.
Test suite passes now, but there may be some stuff left, so we will run
a few sites on a branch prior to merging
