For example, creating a new p4est connectivity, a new mesh, refining/coarsening, load balancing etc. are very common operations and might benefit (a little) if cached? OTOH, the functions are all dead simple, so we might not gain much. I was just thinking about it since I saw the following line in @time_imports Trixi:
0.7 ms P4est_jll
97.8 ms P4est 17.56% compilation time (100% recompilation)
If we should do this, a good set of functions to start with are those used in Trixi 😬