Why does water take so long to heat up or cool down?
Consider the intermolecular forces between molecules of water.
There is a very strong
(that's from my biochemistry book, this stuff still matters!)
Hence, all of these relatively strong intermolecular forces need to be overcome in order for the kinetic energy of the molecules (over a standard distribution) to increase, hence increasing the "temperature".
To be sure, the rate of heat energy addition to the system (if constant) will take longer than if we were heating petroleum ether in the lab. That's why I didn't like general chemistry lab, we always had to boil water!