No Sidious was trying his hardest, stated by GL. What Windu was doing was using his Vaapad style to use Sidious' dark side power against him which is the only reason why he won.
Windu won the duel sure, but he lost the fight. He wasn't going to win. They actually dueled as perfect equals, infact Windu only won by exploiting a fear in Sidious which wasn't even there to begin with. But lets not continue this, it is for another time.