Hi liotta,
I see from your profile that we are both Pompey boys, (for the uninitiated that means we are both from Portsmouth).
There are some missions where the best times are still genuine. One of them is 'A New Fast Ferry Service' in Marsielle. My claim to fame is that when you select that mission my name will be on it as the fastest time, (I hope!, I haven't checked it lately!!), I didn't cut any bouys and when I achieved it my processor was only running at 50%, (as I've recently found out in another topic on 'Technical Support'). Your processor speed effects the speed that you can get out of your current vessel by 2 or 3 Kn in a mission. There are other factors, the Codecs you have and some 'in game' settings that you can adjust. In fact I think I would be safe in saying that all of the 'Red Funnel Cat' mission times are fair and can be beaten. One of the things that you cannot do with the 'Fast Cats' is "go through the game like a ball in a pinball game", the 'Cats' are very easy to damage and any damage has an effect on speed and so defeats the object, (there are also some traps, (invisible Way Points?) that can stop you completing a mission.
Having said all that, I would be very happy to vote for the high score table to be reset when the 'New Horizons' addon is released and clear the way for a fair start for everybody, maybe have one of the 'Global Moderators' monitor it and delete any obviously silly times.