Is it possible to have transaction speeds below a second and still have it secure? Bitcoin has a transaction speed of about 10 minutes per transaction.
if it's centralized, sure.
Also Ripple has instant transaction verification, and it's decentralized (in theory), as it's practically a web of trust. Banks could implement Ripple, or just rip (ahem) it off.
Only the standard for the protocol etc will be centralized; the actual operation of the virtual currency will be decentralized it seems:
"A governance authority may, at first, appear incompatible with the conceptual origins of VCs as a decentralised scheme that does not require the involvement of a central bank or government. However, the mandatory creation of a scheme governance body does not imply that VC units have to be centrally issued. This function can remain decentralised and be run through, for example, a protocol and a transaction ledger." -- pp. 40: http://www.eba.europa.eu/documents/10180/657547/EBA-Op-2014-08+Opinion+on+Virtual+Currencies.pdf
I wonder if the currency can remain decentralized and have super fast transaction times of under a second. Maybe it's possible! The miners don't have to function exactly as in Bitcoin. Some proof of work algorithm would probably still be needed though for security reasons.