Two key concepts in the production planning and control literature that incorporate an order
release function are the Theory of Constraints, with its drum-buffer-rope release method, and
Workload Control, with its load-based release methods. When order release is applied, jobs are
not directly released to the shop floor – release is controlled to realize certain performance
measures. The performance impacts of drum-buffer-rope and Workload Control order release
have been assessed separately, but the two approaches have not been directly compared in one
study. This is a major shortcoming that leaves practitioners without guidance on which release
method to select. This study assesses the performance of drum-buffer-rope and Workload
Control release in a pure job shop and a general flow shop with varying levels of bottleneck
severity. Both bottleneck oriented and non-bottleneck oriented Workload Control release
methods are included. Simulation results show that Workload Control release methods lead to
better performance than drum-buffer-rope if bottleneck severity is low. But Workload Control,
including its bottleneck oriented release methods, is outperformed by drum-buffer-rope if a
strong (or severe) bottleneck exists. Workload Control gains an advantage in balanced shops due
to its unique load balancing function, which attempts to evenly distribute workloads across
resources. But this becomes functionless when there is a strong bottleneck. Our sensitivity
analysis suggests that the performance differences between release methods are not affected by
routing characteristics or the proportion of jobs that visit the bottleneck.