Multimember execution is resource expensive

[scarlehoff]

I'm not sure how to go around this because multi-member means, by nature, many grids have to be loaded in memory at once (if we want to run the interpolation of all of them) as a result the graph is humongous.

Maybe it actually makes sense to fallback to eager mode in this case. Or to tell the user that's an option.
Admittedly the usual scenario for a MC where vectorization is important is to ask for many values of x (and maybe q) at once, asking for many members (order 100) for a few members of x and q is quick even sequentially so run_eager in this case seems a reasonable option.