Is room.SetCustomProperties costly?

A question, can I use PhotonNetwork.room.SetCustomProperties at rather high frequency, or should I add my own caching layer that sort of first bundles up the changes and then transmits them in intervals of say 10s? (Typical specific frequency are not known yet by us, as this is for a sandbox universe where people can invent their own creations.) When I say costly, I mean e.g. much faster bottlenecking/ much slower than the normal RPCalls where a max of 500/s/room is fine. Thanks!