Phone is lagging sometimes

I got a new battery (a while ago)

It works like new, but recently my iPhone 7 started lagging for no reason

Its only lagging when i,m touching the screen, and now it,s randomly restarting when its on charger.

When it,s lagging its like 5-15 fps, My screen is a good 30 euro screen,

is it the battery that causes all this?