Across 5 different computers ranging from 12 years old to less than a year, I can play dod on all of them. 4 are built for gaming, one is a super crappy laptop. Is performance great on all? Nah, but it's playable! It strikes me odd anyone would find it unplayable unless on a truly ancient rig.
So, yes an issue like this would benefit greatly from PC specs posted, because more than likely it's a hardware or OS issue. And if that's the case there is usually a way to tweak and help with the issue. Not always, but many times.
And tbh comparing legacy to the new branch isn't really ever going to be fair. UE5 is simply more powerful, period. Legacy will pretty much always run better in terms of performance because it's on a much much older iteration of the game engine, and at this point has fewer mechanics and assets.
So posting the specs you're working with will help figuring out where issues stem from tremendously.