Welcome to @toly, co-founder of Solana!  

He’s kindly agreed to do an AMA. Reply with your questions. :)

How do you view the importance of centralization / cost / performance / security? As in, which should take more weight on the balance?

The goal of decentralization is to make faults impossible.  I don't see this as a tradeoff for performance.  In fact the higher the performance the more participants can be synchronized, and the faster they can be synchronized, which reduces the likelihood of a majority fault.

I see the purpose of decentralization is the same as fault tolerance.  The meaning has expanded to include things that are academically hard to quantify, like if the majority of nodes are faulty, which could mean censorship or trying to commit an invalid state transition, etc..