With no intention to push back on Emacs being highly optimized, age of an application is not an accurate proxy for level of performance. If it were, grep would be faster than ripgrep. New software can apply optimisations discovered over the previous 40 years, and leverage architectural designs with different assumptions, like the GC limits in Emacs discussed elsewhere in the comments. Older applications can apply those same optimizations, but it's not a given that they will, and changing their architecture can be daunting, for sometimes unknown benefits.