When we migrated from WMB7 to IIB10 we had performance issues when using additional instances and a PMR was opened. What we found out was that when there was a requirement to utilise the additional instances there was a pause in process whilst they were initialising. After a lengthy PMR, someone in IBM eventually put their handup to changing the process under the covers of how the additional instances started up and the solution was to tick the box to have additional instances start when the flow starts.
With a move to PowerVS, essentially AIX on in the cloud, on the horizon, the charging model will be changing to a pay for what you use. Is the startup of additional instances still the same as IIB10 or has it reverted back to the way it worked in WMB7 otherwise we will be paying for the additional resources required for additional instances when demand doesn't require them?
This question is probably applicable to other OS's as well.