Generation speed in Documenter for .NET is dramatically optimized - up to 20 times faster - with Word 2003. The previous Word versions, Word 2000 and Word XP, are also fully supported with exactly the same document generated. However, the generated document is slower with old Word versions. This dramatic speed enhancement in Word 2003 is due to using the new XML features (internally in Documenter and therefore transparent to the user) that are only available starting with Word 2003.
Please note that only Generate New Document is optimized with using Word 2003 XML features. Regenerate Existing Document has the same speed with Word 2003 as with earlier Word versions. However, Regenerate Existing Document is usually very fast as it is, without additional optimization.