Build 35 introduced significant improvements to volumetric cloud rendering. DX10 handles clouds differently than DX9, but FSX never implemented it correctly. The Fixer smooths out the "clumping" artifacts, eliminates the blocky white shapes, and allows for dense, immersive overcast layers that perform significantly better than their DX9 counterparts. This not only looks better but drastically improves frame rates in heavy weather scenarios.

Be cautious of websites claiming to offer "Free Software" downloads for Build 35, as these are often unauthorized and may contain malware. A technical view - Steve's FSX Analysis