Prioritize faster Jenkins workers over slower ones
Since iguana joined our CI menagerie, for the first time we have Jenkins workers with greatly varying performance: workers hosted on iguana are much faster than those hosted on lizard.
It would make sense to let Jenkins know about this, and prefer running jobs on (idle) iguana workers over (idle) lizard workers.
The "Scoring Load Balancer" Jenkins plugin seems to allow this via its "Scoring by Node Preferences".
I think it's worth giving it a try, without investing too much time into it: if it's a low-hanging fruit, then it's a very interesting one; but if it's costly to implement, I would say let's not bother and reject this issue.