using an NVIDIA GTX 480 Fermi card, and in terms of speedup, we obtained 155x from an optimized CPU sequential version running on an Intel Core 2 Duo E8400 at 3.0GHz.

What is remarkable about the speedup is that it allowed us to explore bigger systems, simulate more iterations, explore parameters in a finer way, and all of it at a relatively small cost in terms of time, hardware and coding effort. With this extremely well performing algorithm we obtained a positive numerical evidence of the persistence of metastability in the thermodynamic limit for $q>4$, according to Binder’s criterion.

The paper is structured as follows. In Section \[model\] we briefly review the main properties of the Potts model and the particular physical problem we are interested in. In Section \[algorithm\] we introduce the simulation algorithm and in Section \[validate\] we compare the predictions of our numerical simulations against some known equilibrium properties of the model to validate the code. In Section \[performance\] we check the performance of the code. In Section \[metastability\] we present our numerical results concerning the metastability problem. Some discussions and conclusions are presented in Section \[discussion\].

The q-state Potts model {#model}
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The model
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The 