Sakura will charge her seal faster.
First time Tsunade released her seal :
"I've been gathering my chakra to the seal on my forehead for quite some time"
This shows that it takes time to create a seal that has enough chakra in it. Remember tho, her seal was visible because she is using it to look younger.
Next time we see her use it in Pain arc, and she is fully charged back by the time War starts which is maybe 2-3 weeks later.
I am thinking that filling the seal with chakra for the first time is like making a tunnel, you have to make your way through. But once the tunnel is finished there is no need for that, you just go right through it which is a lot faster.