Auto-Select game Detail vs High, Med, Low

So I was having a problem with game speed on my laptop & upgraded to 2.5GM of RAM (from 1GM).

I was expecting a HUGE improvement in 3d match speed/fluidity. I decided to increase the game detail setting (I think that's what it's called under Prefs>Display menu) from Auto to high.

Despite adding 2GM of RAM this caused the game to be jittery & nearly unplayable.

I left the crowds, stadiums, weather & sky effects on, & went back to the AUTO DETAIL setting & the game plays more smoothly.

Has anyone else experienced this? What is the difference between the AUTO & High,Med,Low detail level selections?

Personally i see no difference on my pc when i switch between detail levels but i havent played around, but due to my high-end desktop i just leave it on high setting with all the possible 3D options.

I would say that RAM on its own does not increase 3D match performance.