This is a companion paper of [1] and [2]. In the cited papers, using the C-algorithm introduced in [3], many new examples of isochronous centers for Li´enard type equation are found. The application of C-algorithm needs intensive use of computer algebra investigations. In this note we present a low computational cost variant of C-algorithm on which the computations presented in [1] and [2] are based. Mathematics Subject Classification (2010). Primary 34C15, 34C25, 34C37. Keywords. isochronous centers, Urabe function, polynomial Li´enard type systems, computer algebra, Maple.