Faster block time in mainnet GA

[ranchalp]

Description: Optimize network layer, consensus step, PoSts, etc. in order to reduce epoch time and provide faster block time.

ETA: 2024-12-31 Maintainer: @ranchalp

### Milestones
- [ ] Explore optimization opportunities across stack
- [ ] Consider optimizations in network and dissemination layer (Byzantine broadcast, Narwhal-like, etc.)
- [ ] Come up with proposal
- [ ] Settle on requirements and assumptions
- [ ] Propose design
- [ ] Prototype and test
- [ ] Mainnet release

Known dependencies:

• None