I’ll add to this as I think of more things.
(*) vraylog level 4 isn’t really helpful in optimising your scene. Sure you can see any errors and obvious slowdowns, but nothing specific like how long it’s taking in miliseconds for each map and so on.
(*) Add a CPUTime render element, which shades the pixel according to it’s rendertime. Renderman has something like this. Normalize by total rendertime if it’s possible to do this (it would obviously have to be done at the end of a rendered frame). Maybe in the element options you specify an expected rendertime or max time or something, and it uses that to normalize by so you can see it as the buckets render.
(*) Add MemoryUse render element, which shades the pixel according to it’s memory use. Normalize by total system memory OR user-entered Dynamic memory limit.