I have heard, a number of times, people say that "science" says you should salt your pasta water 'cause it'll make your pasta cook faster. Weirdly enough, this is one of those ideas that is actually both true and false. See adding a solute, like salt, to a solvent, like water, can change the properties of that water. Properties like boiling and freezing points. 

And yes adding salt to water makes it boil at a higher temperature which would cook your pasta faster. But it turns out you need a lot of salt to make that happen, way more than you were going to use. Adding the amount of salt that a nearby box of pasta told me I should add would only increase the boiling temperature by like 0.05 degrees Celsius, which is way less than just like going up or down in elevation. 

This is not going to result in a noticeable difference in cooking time, you should however, salt your pasta water. Why? Well, for the same reason we salt all other things. It tastes good.