Load = total weight of engine, gear, fuel, passengers and hull.
There are calculators on line that allow you to input hp, hull type and total load
that will spit out what you should be able to get for top speed.
http://hhscott.com/evinrude/docs/BSLAC.htm
Knowing what you should expect from a 35 pushing your specific load
will tell if there is a problem with the engine, or if you need a different prop to up rpms.