The rate of digestion depends upon the surface area of the food particles, and yes, its temperature, with the ideal temperature for gastric emptying being on the warm side (~43°C), but not hot. Similarly, enzyme activity is at its greatest at around core body temperature (~37°C) or slightly higher (~42°C), depending on the enzyme. However, the mechanical action of chewing breaks the food down into progressively smaller pieces, vastly increasing its surface area, and consequently the rate of chemical reaction. And since the rate of temperature change is also associated with surface area, and exponentially with temperature difference, the act of chewing very quickly normalises food temperature with body temperature. The temperature of liquids similarly normalise rapidly. The temperature of liquids has been found to have either no effect, or otherwise a small effect on gastric emptying, when the temperature is particularly low (4°C). And thus for the aforementioned reasons, properly-chewed food should be expected to have a similarly insignificant effect on digestion time, absorption time, and hence efficiency.