o Loading macros from preamble for every completion is slow (see profile).
o Calculating macro USR is also slow (see profile).
o Sema can provide a lot of macro completion results (e.g. when filter is empty,
60k for some large TUs!).
o Slight memory increase in dynamic index (~1%).
o Some extra work during preamble build (should be fine as preamble build and
indexAST is way slower).