In reality the lifecycle of a transaction is more complex, however we can see that the most significant time is taken by consensus. The complexity of it comes down to a few portions: 

1. Transaction Creation / Submission (negligible time)

2. Mempool (1-N seconds, highly variable)

3. Block Proposal (negligible time)

4. Attestation and Block Building (~12 seconds)

5. Block Finalization (minutes to hours)

The fourth step here is the main focus of this blog post - consensus. On Ethereum, the process of validators attesting and building out a block takes 12 seconds in total. 

In the case of Sei, Sei Labs opted for a different consensus mechanism to Ethereum, known as “tendermint consensus”, which has a 6 second block time.$SEI