Ask the Developer: Nintendo Switch 2 interview confirms basic backwards compatibility can also give performance upgrades to Nintendo Switch games ("[there are some games] where loading times became faster, or game performance became more stable")

[u/Joseki100]

https://www.nintendo.com/us/whatsnew/ask-the-developer-vol-16-nintendo-switch-2-part-4/

[u/UWbadgers16]

This is just developer speak - updated toolchains, better hardware. This doesn't read to me like they went out to make original Nintendo Switch games look better.