I just read a fighting manga where 2 characters fight after years. For context the 1st character is much older than the second (about 15 year gap). The second character is about 22 years old at this point. That older character said this line.
I understood the 1st line as "How the hell did you get this strong?" or like "To think you'd get this strong." Please correct me If I'm wrong.
The second line is what I have trouble with. My guesswork understanding would be "It would've been good if you had attacked me earlier." But can さっさと function as earlier? I've only so far heard it as "hurry up" and only used it by itself.