I think this could be a part of the compulsory tutorial, swapping settings from high graphics & poor performance to low graphics and better performance. This part of the tutorial would allow the player to set it as s/he likes afterwards, but would raise awareness of the option and its connection to lag.
Coupled with a warning popping up now and again, it could really help those who get lag issues.
(I voted 'tweak' but can change to yes if it looks like gettin close to the mythical 30 votes)
I agree – the tutorial is a good place to put this message, but sometimes people forget/do not pay attention to the tutorial. I think having as many fail safe mechanisms in place is the best operating procedure, so that if one person does not pay attention to the tutorial, they will have the default at a less laggy spot.