You could compare it to Windows vs. Linux in a sense. 3ds Max has decades of legacy plugin/SDK compatibility baggage, lots of commercial and contractual obligations with business/enterprise customers... and Blender has none of those things weighing it down.

Well, I have been using 3DsMax and Blender from the early versions and it's always been the case that Blender is way faster.

Legacy baggage has nothing to do with it, in my opinion.

Ha, I'm always struggling with UI performance in Blender. Undo takes ages and freezes up everything, modifiers start lagging mouse movement as soon as you have more than a handful of polygons. I shudder to imagine what Max must be like.

Though I must admit you can have an absolute shit ton of ridiculously complex objects in a scene, and it will run smoothly if none of them is in edit mode which is at least fairly impressive.

Fun blender fact: every .blend file contains a serialisation of the complete data model of the blender version that wrote it. That's why they have a minimum file size of about 280kB.