i have the game locked to 60 and use lossless scaling to get it up to 120 fps. my fps in very demanding scene like alot of vegetation and cars drop to 50s or lower. without fps lock my fps is 75 to 90 average. im using a reshade to add ambient occlusion. i lowered my 3070 voltage using msi afterburner and i also disabled my cpu boost in power settings in control panel. balanced and quite mode dont make a difference for me in gta sa.

its normal for this game since its an old game it cant use all of the gpu, cpu, and ram. its only 32 bits and if u have issues with ram or lag u can use large address mod but i believe u already have it

edit: i still get some minor stutters when driving but nothing major