How active was the Milky Way in its first 5 billion years? When I look into the history of the Milky Way, it seems like the Milky Way has been the pinnacle of stability. It seems highly likely that our galaxy has eaten several smaller galaxies/dwarf galaxies in the past. Also, our galaxy seems to be one of the first to form. I am wondering if our seeming stability is the result of our galaxy's age. So, was the Milky Way more active (as far as stellar formation, supernovae, etc.) in its early years? How do we/ could we know?
Although the question was asked a while ago, it still sounds interesting, so I did a bit re-search and I found a Nature news-feature by Adam Mann: Hidden history of the Milky Way revealed by extensive star maps

The team had spotted a set of 30,000 renegade stars. Unlike other objects in the main body of the Milky Way, which orbit in a relatively flat disk shape, these non-conformists were moving backwards, in orbits that were carrying them out of the Galactic plane.
Within weeks, the team had worked out that the luminous horde pointed to a long-hidden and especially tumultuous chapter in the Milky Way’s history: a smash-up between the young Galaxy and a colossal companion. That beast once circled the Milky Way like a planet around a star, but some 8 billion to 11 billion years ago, the two collided, massively altering the Galactic disk and scattering stars far and wide. It is the last-known major crash the Galaxy experienced before it assumed the familiar spiral shape seen today.

The highlighting in the quote is my attempt to answer your question - it is not talking about the Milky Way's first 5 billion years, but it somehow implies that its early history might have been indeed turbulent.
References
The original article is by Amina Helmi et al. is called The merger that led to the formation of the Milky Way’s inner stellar halo and thick disk