How do you mean 'Red'?

But it's good it's full. You're not supposed to write anything into it, so if it's 100% full right from the factory, that's 0% of your disc space wasted.
Since you're only supposed to boot from this partition, it isn't even to have a look into it. That's why it usually is a hidden partition. Why did you unhide it?

And since it's never used, it doesn't influence the speed of your PC in any way.

Something seems wrong here.