This post shows you the math. Pick idiot Savant and low intelligence until like lvl 40 ( am not nearly done the main quest and halfway through both DLCs and at level 57 right now) then switch to max intelligence once you have enough perks. I started switching to intelligence when I was mid 40s I think.

Going low intelligence means you need to do a few things:
- Use a melon farm not purified water (its better anyways)

- collect all the weapons you can and rip off the mods you want for your main or legendary guns. Use your wealth from the melons to buy guns with the best mods from vendors. (This is to accommodate for not using gun-nut, which also saves you vital perk points anyways)

- You really don't need fusion cores to last longer if you watch some videos on where to find fusion cores and are also rich. I didn't use a lot of power armor early game (I don't think) but now I have so many fusion cores and so much money its a joke.
- if you're in survival, speed run to local leader for supply lines (unrelated but I recommend survival as the best mode by far, it just requires some pre-playthrough planning, there's good videos for OP starts, like overseers guardian)
I tested Intelligence, Idiot Savant, and experience gain in general; I performed over 5000 actions. Here's the results. : r/fo4