There is this Heavy Job Plugin, which defines a Job property for FreeStyle Jobs that causes additional  executores to be required for a Job execution. This is useful if Jobs differ widely in the load that they create on the slaves.

It would be nice to have this also for the node() groovy command with an optional argument, say 'weight', that, if used and larger than 1, causes more executors to be used. The code can largely be leveraged from the Heavy Job Plugin. AsynchroneousExecution exception is your friend.

Extra cool would it to allow for weight=0 to cause a FlyWeightTask to be created that does not use an executor.