  The time complexity of the presented in 2013 by the author small universal
Petri nets with the pairs of places/transitions numbers (14,42) and (14,29) was
estimated as exponential. In the present paper, it is shown, that their slight
modification and interpretation as timed Petri nets with multichannel
transitions, introduced by the author in 1991, allows obtaining polynomial time
complexity. The modification concerns using only inhibitor arcs to control
transitions' firing in multiple instances and employing an inverse control flow
represented by moving zero. Thus, small universal Petri nets are efficient that
justifies their application as models of high performance computations.
