Lag time of Exchanges during Crash

I'm registered User of the 3 main Exchanges the "good old" mtgox, Bitstamp, btc-e.
I'm registered at mtgox since 2011. I newly registered with bitstamp and btc-e. I have money in none of these accounts, so i couldn't play around today.

What i'm really interested is to find the most reliable exchange in terms of lag time. It is easy to have an O.K. trading experience (compared to stock market BTC is really horrible) when market is doing normal. But when price like today cuts itself in half in short period of time - the slaughter/Problems begin.

I was watching a lot today on bitcoinity how those three Exchanges where doing in regard to lag time - but its difficult to learn something from there. Is really the underlying exchange lagging or is just bitcoinity lagging, or is just the API for the quotes of the site lagging or is actually trading lagging etc. etc.

Logging in to the sites was not so informative too since i didin't have funds in them.

Has someone experiences/ideas how to come to a conclusion how those 3 mentioned exchanges will perform during next crash? Any measurements ideas etc.?

And yes i do know that the future is hard to predict and it depends on so many factors, but that's life you have to make decisions...