Optimizing dynamic sitemap generation for Laravel SEO performance?

hey everyone, i'm pretty deep into building out our 'Dynamic XML Sitemap for Laravel & All Websites' solution and hitting some serious walls with scale, specifically around large-scale dynamic sitemap generaton for millions of URLs. the whole idea is to have a robust, auto-updating system, but the practicalities of performance and scalability are a nightmare, especially for big sites. the main problematic is definitely around efficiently generating and serving these sitemaps and accurately determining and including the lastmod attribute for each URL without just absolutly trashing the database with excessive load. we've tried a bunch of things, you know? we've implemented real-time sitemap generation with pretty aggressive caching, using both Redis and file-based methods for sitemap segments, which helps a bit. we also made sure to utilize database indexing on the updated_at columns for all our relevant content models, thinking that would be a silver bullet for faster lookups. and yeah, we've even experimented with queueing mechanisms for background sitemap regeneration whenever content updates happen, trying to offload the heavy lifting. all these steps are good for general Laravel optimization, but they don't quite solve the core issue. but the real, persistent technical block is still that darn lastmod attribute. how do you efficiently track the absolute latest modification timestamp across potentially millions of dynamic content items – think products, articles, user profiles, whatever – without causing massive read storms on the database during sitemap compilation? our current approaches either lead to stale lastmod dates, which defeats the purpose for SEO, or the sitemap generaton times become unacceptably slow, which is just as bad. it's like we're always choosing between accuracy and speed, and neither is truly acceptable for a robust solution. we need something that scales properly. so yeah, i'm really seeking advanced strategies or architectural patterns here. what are people doing for managing and retrieving these lastmod timestamps for large-scale, highly dynamic Laravel sitemaps? how can we minimize database impact and ensure optimal Laravel SEO while maintaining absolute freshness without breaking the bank on infrastructure or performance?