Since warmer air has a higher moisture holding capacity, increasing the temperature will lower the overall humidity inside the dehydrator creating more capacity in the air to accept the moisture from the food. However, higher temperatures also kill enzymes that are beneficial, but that typically relates to “raw” food diets which suggest a temperature of 118 degrees or lower, which is not a common temperature for backpacking purposes.
The more important reason not to crank it up is case hardening, which occurs when the temperature is too high and dries the outside of the food too quickly. This creates a shell or “case” that slows down or completely stops the inside from drying. If this occurs the food may appear dry, and then spoil when you store it because it’s actually still moist.
The best way to speed up drying is to put less food into your dehydrator, get a bigger dehydrator, or increase the surface area of your food by cutting it smaller and spreading it thinner. Of course which method you choose depends on why you want to speed things along.