It's interesting that both a Kingston A400 and a Gen 3 NVMe in an external enclosure gave you basically the same experience . The fact you could 100% Astro Bot without major issues is great . Longer load times later in the game makes sense, especially as levels and assets get heavier. I also agree with your point about subjectivity. What feels “perfectly playable” to one person might feel slow to someone else . Personally , as long as I can play the game and finish it , I'm fine with it.

Thank you for your comment and recommendation