Yes. I completely agree with you. I don't understand why superfast trains in Kerala are so slow, even for trains having just one stop in every 100km. Tamilnadu express takes just 6 hours between Chennai & Vijaywada for a distance of 430km, as Managala Express takes 9hours to cover a distance of 417km between Mangalore&Ernakulam. It may be due to the tracks are not fit for speed more than 110kmph or due to the poor quality or railway lines.