  In this paper we present FASE (Fast Asynchronous Systems Evaluation), a tool
for evaluating worst-case efficiency of asynchronous systems. This tool
implements some well-established results in the setting of a timed CCS-like
process algebra: PAFAS (a Process Algebra for Faster Asynchronous Systems).
Moreover, we discuss some new solutions that are useful to improve the
applicability of FASE to concrete meaningful examples. We finally use fase to
evaluate the efficiency of three different implementations of a bounded buffer
and compare our results with previous ones obtained when the same
implementations have been contrasted according to an efficiency preorder.
