I'm surprised people don't mention about Compact block when we're talking about block propagation, block size and scaling. But it's not applied for nodes that just went online though

1. Block propagation is very fast as compact block have very small size (AFAIK about 10-30KB for 1MB block size)
2. Block verification time is fast as all transaction inside block already confirmed when it's broadcasted
3. AFAIK both block propagation and verification time should take less than 20 second (based on a presentation/conference video i've seen few years ago)

Regardless, few things such as Initial sync is serious concern as it took few days to few weeks (depending on internet speed, storage speed, etc.)