Fallout 3 pc lag please help?

Right ive had my laptop for 2 years now and ive had the lag for 2 years dont know why ive put up with it. my laptop is AMD turion dual-core RM-72 2.10GHZ 4GB 32 bit Windows vista home premium and the graphics is Nvidia 8200M G ino its not very good and i should buy a new one and i will have too soon. ok the wierd and long bit lol. note: my graphics drivers are up-todate ,heat levels fine , tried overclocking (still do) adjusted every nvidia control panel option, done mods etc, stutter remover, 4gb allower, lots of tweaking, ini changes, performance mods, and MUCH more as ive had it for 2 years LOL . ok ingame , 640x400 resolution low settings (with changes) like depth fog and stuff otherwise it looks horrible, oh yeah ive got mods that remove lighting, effects smoke and stuff . MAIN THING- i run at 30fps max because stutter remover caps it and its fine most of the time in the whole game, mostly at 27-30 frames average which is ok, but now the stupid things, extreme lag in megaton house, citadel, vaults, most indoors, usually places with big halls and big areas, and also in silvers house, (near start of the game ) her house is tiny, VERY tiny, good max frames, look around, small lamp in distance BOOM 15-23 frames i mean wtf ? as well with lag in big areas, the graphics card isn't that slow because these are the clocks- normal- core clock, 400mhz -memory, 800mhz- and shader clock - 800, BUT that is pretty slow, and my laptop is used to playing on: core clock, 520mhz-500mhz memory, 800( i dont change that) and shader-1250, and it works well, please help me to whats going on i use game booster, no open programs plenty of memory ive tried everything seriously lol im prety good at computers so feel free to ask anything to complicated. any help is HIGHLY appreciated.