Another idea thrown against a wall:
can template scripts be "pre-calculated" ? I think most people talk about script interpreted "on-demand". But what If scripts are updated every 100 uses, and in a async way. That way a script that take 10 min to finish is not a problem. It will be updated every 10 min (or every 1 hour, if the servers want that).
I mean, have "outdated" templates, that only updated wen the server can, and not everytime the server use that template.
note: I have no idea if this message is more noise to make the raise/signal worst. Sorry if is that.