I switched servers recently, and for some reason XML-Sitemaps runs way better now. Not a whole lot different in the configuration, but maybe it really is CPU intensive... Went from a 2-core system to an 8-core system.
You can generate a home page, and then in the build directory page, so you can be greater than 500 pages
try to use with php coding so it will take your hosting use and give you more and more site map genrate.....
sitemapGenerator.jnlp It works great, a bit slow for sites larger than 50k pages, though. It may take 2 days to complete. BUT IT DOES.
Just write a script that generates it from your database entrys, and make it auto-updateable. Thats the easiest and most effective way!