The most real-time consuming action is not the pure download but the signature-verification for each TX-out in a block since bitcoin-0.8.0
(I wrote my own independent blockchain-parser and did all kind of verifications & checks) -- assuming you have a reasonable internet-bandwith connection.

Therefore you could simple fetch a "verified" blockchain (including a special PK-signature) by downloaded it from a trusted website(s) and only these web-sites need to update this block-chain-file(s) increamentally for public use. Then there is no signature checking necessary from the client anymore and you have a huge speed improvement when using the blockchain data.

Well, I wrote "trusted" website (by you). You doesn't trust ANY website in this matter? Then I wonder that you are using the bitcoin-client. Or are you really one of these extremly rare people who indeed checked all the source code of the bitcoin-client for a back-door or have you written your own bitcoin client?  

smtp