I've downloaded the list of all trades executed on Mtgox over the past 24 hours (there's an API URL for that), and wrote a tiny script to count the number of trades during every 1-minute interval.
Turns out, the single worst minute saw SIX trades per second. The top 15 worst 1-minute intervals saw an average of 3.8 trades per second.
Let's try to estimate how many trades per second their engine is capable of. The worst lag I saw over the past 24 hours was about 500 seconds, i.e. 8 minutes. Let's simplify this a lot, and assume that this lag was created after the worst 1-minute interval, when Mtgox saw 370 trades. In the most conservative scenario, a lag of 8 minutes would mean that these 370 trades took 7 minutes to execute (this is a bit of an approximation, but I think it's close enough).
That places the Mtgox trading engine speed at just 0.9 trades per second.
This is so ridiculous that I have to wonder if I made a mistake somewhere. But if I didn't, their trading engine was written by monkeys (something that everyone seems to agree on anyway).
EDIT: I've had someone question the approximation, so I wrote a better script. This one iterates 1 second at a time, queues the trades arriving in that second for execution, then executes trades from the queue at a specified speed (seconds per trade). It then measures the lag directly. Using
this code, to get the worst lag of 500 seconds, "seconds per trade" is 0.65, i.e. approximately
1.5 trades per second. But I doubt 500 seconds was the worst lag during these 24 hours...
EDIT: if the worst lag during these trades was 50 minutes as suggested by 2weiX, that places the speed at pretty much exactly
1 trade per second. Hm... how suspicious... (might be an accident though)
