biofuel refers both to the source of the fuel, as well as (currently, at least) the compounds contained in it. If the production quality is strictly controlled, eventually there should be no detectable difference between a fuel mixture derived directly from biological sources, and one derived from petroleum products (which, technically speaking, are of biological origin themselves, just a few million years removed). However, due to technological limitations, biofuels and petroleum-based fuels do have different chemical components today.
The reason we hear of differences in mileage or "energy density" in biofuels used to power automobiles as compared to gasoline/petrol is because they are not the same mixture of chemicals. This page goes into detail (the whole site is actually quite clear with its explanations), but the basic difference is that petroleum products are essentially 100% hydrocarbons (only containing hydrogen and carbon atoms) while nearly all biofuels contain oxygen as well, which has numerous effects on the fuel's physical and chemical characteristics, altering everything from polarity to reactivity to stability over time to the types of byproducts (and pollutants) produced during combustion.
There is much more to the story, but the basic answer to your question is yes, biofuels could replace petroleum-based products for aviation and many other types of fuels, and not impact the maximum speed of the aircraft. It may require engine modification, and the energy density may not be exactly the same (possibly reducing range), but for the long-term health of our planet we MUST reduce and eventually eliminate our use of petroleum.
By the way, the Aviation or Chemistry StackExchange sites would likely be able to provide you with much more in-depth answers, as ultimately this question is better suited to either or both of those sites than Biology, which would be more concerned with the production of biofuels by living organisms.