ATI 5450 was/is(back to 2010) low budget video card which means 3D games aren't target of that model.
No matter size of memory set 512MB, 1GB or even 2GB bus type is only 64 bit what make most games unplayable , even videos on youtube lags if you try play them with HD settings.
SA isn't running good on older ATi graphics cards.
My HD 5450 should be able to get 90-100 FPS all the time, but it drops down to nearly unplayable once the smoke effects comes in.
My older GeForce 8400 GS is able to get such FPS.
If we talking about previous series of ATI, for sure you couldn't expect good FPS in class of 9200SE/9250 what were released in time of game, but 9600XT/9800PRO gave decent FPS.
Seriously i have no idea why all bother to play online game with hardware old 5 or more years, and whose price is 30-40 euros in total(PC) while you pay internet like half of that every month... to even browse this forum
Bottle of Coke and pizza cost you 5 euro every day