If you just need a small download size for slow internet, the FitGirl repack is the safest among unofficial options. But for security, the official version + external compression tools is better.
Better optimization for modern multi-core processors. How High Compression Works metro 2033 redux highly compressed
While "highly compressed" versions (repacks) are often sought after to save bandwidth, they can be risky. Users have reported issues such as missing .exe files If you just need a small download size