Quote Originally Posted by Ryihito View Post
Food only provides a very minimum boost. it's only useful for the 3% EXP boost.
What!? I think you're referring to low level food/character since this is posted on New Player Help, but as you can see OP is Bard 50 and asking about food and speed runs.
On topic, I feel it's that linear, but take this with a grain a salt since I'm not fond of theorycrafting. I guess you should use Black Truffle Risotto HQ. Anyways, you should get more accurate information posting on DPS roles forum.