I don't think it's due to a lack of competitors that we don't have faster clock speeds but because increasing the clock speed causes the CPU to get too hot, and

I don't think it's due to a lack of competitors that we don't have faster clock speeds but because increasing the clock speed causes the CPU to get too hot, and its difficult to actually get better performance that way. At least it's something along those lines according to several of my previous Electrical Engineering professors.