This is a limitation due to how 32-bit systems handle memory. In a 32-bit system, there is a maximum 3GB of RAM that can be directly address by the system. Since we've added many new features to the processing capabilities of DxO Optics Pro 8, the directly available memory gets full and the software quickly becomes unstable and will crash more often.
The support of 32-bit systems has been greatly reduced by many software manufacturers for major processing needs, especially in image processing. Our competitors have also abandoned operating systems such as XP because of this limitation.