It depends on the application itself. For pages which user will only stay for few minutes, no much more efficiency gained. But for realtime apps which user will keep the page open for hours/days, it will improve a lot. And for apps which have more read than write, it will also improve a lot. BTW, I'm not sure whether I catch you about the "extra code". It's a replacement with less than 1KB difference in size.

Even 1kb seems like too much. The processing power to handle the time ago logic is so small, having to download 1kb of data more probably takes more processing power than you're saving.