What were you cutting, plywood?
Plywood could accelerate the wear on the blades, but if not, that does seem strange. Are they clean and free of any built up gum or sap? Also if making a 3/4" wide pass, it will use a lot of power on the saw, if only a 1 HP motor. Could be several issues combine, but hopefully not premature dulling.
The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)