Each team has determined what 1 Kg means in terms of lap time. Sometimes this is mentioned on the broadcasts. I assume it would also vary from track to track. It could be that the extra 5 Kg would work out to a disadvantage over the course of a race. In other words, you might not be able to make up the early disadvantage. You also have to figure in tire wear. Heavier load means more stress on the tires and probably shorter useful life.
I remember that race were Alonso won with a different strategy, but I suspect that you might need more of a lap time difference between the prime and option tires than they usually have now, to make that work.
And yes, I am an engineer...
Edited by flatlander48, 10 June 2015 - 12:45.