as was said in an earlier post some lifts do have a speed limiting switch on the mast that limits the travel speed when elevated above a predetermined height. Not all lifts are equipt with this option though so by general rule and is taught in every training class given to operators, you should ALWAYS travel with the forks only a couple of inches off the ground at all times, especially when carrying a load. The ONLY time you would be moving the lift is if you are putting your load/product on an elevated shelf and only doing it during that process of inserting it into the storage spot or removing it. You always insure once you have the load on the forks you should always bring it straight down to the floor, or wait to the last instance to raise it, at your first available opportunity to avoid instability factors which are very high when the forks are elevated to a height above the top of the mast.
If you are fully elevated always minimize the amount of traveling you have to do no matter what the situation is.
Note: if a lift has a travel speed limit switch on it then it has to be operational by law, no exceptions, if you find one bypassed that is a huge violation and big fines could be given to the company if not repaired and found this way.