Money spent to reduce deadtime (e.g. greater agitation, faster valves, faster measurements) will be wasted if the controller is not tuned faster. You may have wonderful process dynamics but loop performance will be lousy if the PID is not tuned to be commensurate with the opportunity. A loop with excessively slow tuning and low deadtime will have similar peak and integrated errors for disturbances to a loop with high deadtime but with tuning as fast as allowed. The rise time for set point changes will also suffer. Whereas deadtime sets the ultimate limit to performance as noted in Top Ten Limitations – Deadtime, tuning sets the practical limit. The difference between the practical and ultimate limits can be resolved by an implied deadtime from the slow tuning. If the tuning is set for maximum disturbance rejection, the implied deadtime reduces to the actual deadtime as detailed in the August 2008 Application Note: Effect of Sample Delay on Standard PID Tuning and Loop Performance.
from Modeling and Control