Unlike other SEF components, SEF Advance doesn't store URLs in database to later look them up for conversion. Instead, SEF Advance does all the URL conversions on-the-fly. This method has proven to be more effective in terms of performance because it avoids dealing with database searches on very large, non-indexed, duplicate-entries tables.
Additionally, SEF Advance features disk cache option for further decreasing the load on your database.
SEF Advance has been successfully running on many large sites during the years.