If you have a 4 GB RAM PC, stick to the Classic v1.0 version for the best performance. It only takes up about 4.7 GB of storage and will run flawlessly. Avoid the Definitive Edition unless you plan on upgrading your RAM to at least 8 GB.
Search platforms like YouTube for "GTASA Graphics Mod for 4GB RAM" to find optimized textures that look better without increasing hardware load. gta-san-andreas-4-gb
You may see websites offering "highly compressed" 4 GB versions of the game. While compression technology like the KGB Archiver exists, be cautious: If you have a 4 GB RAM PC, stick to the Classic v1
The Ultimate Guide to GTA San Andreas : Navigating the 4 GB Question gta-san-andreas-4-gb