sitemap generator technical SEO help?

hey everyone, so we just launched our free xml sitemap generator, and i'm pretty new to the whole technical SEO game, tbh. it's been an interesting ride getting this out.

the main issue we're hitting is when folks try to generate sitemaps for really big sites, you know, the ones with hundreds of thousands or even millions of pages. our tool often just hangs or times out completely. it's super frustrating 'cause we want to help everyone, not just small sites. i'm thinking it's a resource thing, maybe memory or execution limits on our server. here's a dummy log of what it kinda looks like:

[2023-10-27 14:35:01] PHP Fatal error: Allowed memory size of 268435456 bytes exhausted (tried to allocate 12345678 bytes) in /var/www/html/sitemap_generator.php on line 123
[2023-10-27 14:35:02] Request Timeout: Maximum execution time of 300 seconds exceeded.

so yeah, for these really large sitemaps, how do more experienced developers or technical SEO pros handle these kinds of generation issues? are there specific strategies for chunking sitemaps, or server configurations that are crucial? any best practices for scaling this? anyone faced this before with their web tools?