Originally posted by mjt
Just to test it out, I bought 100 shares through ARCA when the inside ask was REDI, then sold when the inside ask was INCA. In both cases, it took about 5 seconds. Why would it take this long? I am using IB; I don't know if that has anything to do with it.
100 shares 5 secs? Nope. I have been with MBTrading, now Terranova-MB and I use the RealTick platfrom. At first, I hated to use the old ARCA route because it preferenced MMs as well. But now I use and use only the new ARCA-NOW route which creams off ECNs only (BTW I configured my L2 to only show ECNS, no MMs). Have been using this for 3-4 months now and if the L2 does show the number of shares you need and at the right price/s, enter the order quick and you will see your orderbook fill up immediately (usually 1, at most 2 secs for confirmation of typical 1000 FULLY executable* shares, yes 1000

)
But do bear in mind if the shares available at the executable* prices is thin, there may be some other L2 traders that could have been faster than you. Again, have a look at your Talnet's inbytesqd to see any lag(for realtick users) to make sure your quotes/timesales are timely. You may think you should get an execution on an otherwise lagging quote/timesales
* what I mean by executable prices is buying on ask, selling on bid. No posting (posting or your own market-making depends whether the market moves back to your post for it to execute, that may take anywhere from 1 sec to indefinite

)
I suggest you take yourself to the nearest L2 trading room to see other traders at work on their L2, and see how they react to prices seen on their L2 and how fast they fire an order and how fast it fills up.
I don't use IB, I liken them to Datek Direct. I use Realtick because I can see ALL quotes from ECNs and MMs, and importantly MY own post on the L2 screen, and which other posts on the ask my buy order matches against. It gets no better than that. If you are really serious trying to earn from the market for a living, have a look at L2 platforms. Realtick is one of them which I personally consider the premium solution. You don't need technical problems to give you headaches or confusion when you should really be concentrating on the market instead.