1.52 is a major upgrade to Civ IV and includes numerous optimizations for memory usage that should help performance on all machines but are tailored to especially improve performance on machines at or near the minimum specification.

Major changes include:
-Shared low-level graphics buffers
-Removed many unused fonts and reduced interface memory usgae
-Paged out units which are not visible
-Reduced terrain data size and overhead
-Reduced route data size
-Created a set of low-res movies for machines without dynamic texture support (this is a separate download)