Peppers are one type of seed that really seems to benefit from warmth. Although I germinate almost everything at normal room temperature (or outside), I do use a heating mat for peppers.

Ditto what Neil said. I did not use a heating pad for peppers, but they took 11 days for some of them to start breaking the soil. Some took three weeks. I did have them covered with plastic to make a "greenhouse". Once they germinate, you dodn't need the plastic anymore.