Improved performance is always welcome esp. when trying to keep older hardware useful.
From the Apple web site
“Metal is a new graphics core technology that gives games and apps near-direct access to the graphics processor on your Mac, delivering enhanced performance and a richer graphical experience. Metal speeds system-level graphics rendering by up to 50 percent,4 as well as making it up to 40 percent more efficient.5 Metal allows the main processor and graphics processor to work more effectively together, boosting high-performance apps. And Metal is designed to be great for games, improving draw call performance by up to 10x and paving the way for new levels of realism and detail.”