It also depends on your scale. Optimizing javascript on my blog will probably cost more carbon to keep the laptop on while I work than it ever will processing t

It also depends on your scale. Optimizing javascript on my blog will probably cost more carbon to keep the laptop on while I work than it ever will processing the client JS. The world probably doesn't need my VM running 24/7 on the other hand. My server is in Singapore and in theory that means it's running on natural gas with Singapore getting 95% of it's power from natural gas. Better than coal, but still not great. It's fun to think about how all this software manifests in real world, it's easy to pay it no attention.