Is it still worth it to repair it in 2018?

My iPhone 5c has a broken display and the battery has inflated it self after I stopped using it. But it still seems to work in general.

Replacing the display and battery cost 100 € in a store around the corner.

My question is if the new battery will also give the phone a better performance than it had with low battery (speed).

Im thinking about giving it as a present to my step mom who has no smartphone so far.