Well, imagine it Martinjmpr... :coffeedrink:
The math would make you think it doesn't seem to be a big deal; tables will convince you it's an insignificant number with a decimal point in the middle. Butt-dynomometers vary though, and you will find this a highly contested issue... some will try to convince you they run 37s on stock suspension with a 4 cylinder and AT, and that it runs like a scalded dog.
In the real world it does make a difference. If a response to your question includes, "its not all that bad," or, "I can live with it," than they CAN feel it and the truck IS suffering from it. Ask me how I know...
I said all these things when I ran 285s with my 3RZ AT. As long as I was around town getting groceries and never went up any grade or tried to stay with traffic on the interstate I could live with it.
The fact of the matter is if you have any weight from armor, winch, bumpers, and you have larger than OEM tires you will have a decrease in performance. Your engine and drivetrain will be working harder to push that increased weight against increased resistance. For reference, my truck weighs 4700 lbs as built below with ARB fridge and full tank of gas.
Re-gearing is the solution. It brought me back to stock levels of performance and gas mileage. It's no "scalded dog" but it hangs with traffic on the interstate and my transmission is no longer downshifting at a cyclic rate looking for a better gear for the slightest hill on the road.
We could help (or argue amongst ourselves) more if you described what you drive and any other modifications you've made to it. My signature block gives you an idea what I have and this reply is caveated with "this is my experience," although I am 'more righter.'

Good luck!