Now is when we realize that we are talking specifically about IB in a subforum dedicated to IB issues.
Well I could be mistaken, But I thought it was the case when you place an order it has to be checked for things like margin. And these checks go through the chain of handlers of the order from order creation through to order execution at the exchange. These checks add ms, not many, but some. But if the account already knows what is allowed for a specific instrument, then the check is faster than evaluating the portfolio. This is how a reasonable system would be designed to gain execution speed. But again, this is what I heard, and could be wrong. And it is more complicated, of course. Yes this is an IB forum, but if what happens outside of IB TWS and the API is not relevant or useful, just ignore. Sometimes working to get better speed it is easier to change. I am out.
As I was expecting you have no fucking clue of what happens when your order reaches a broker and tried to mash a few words together.
Agreed. You could have the fastest connection to your broker but if your broker is slow, you are slow. Most brokers will provide metrics on added latency they cause. They will tell you how risk checks are implemented (nothing secret here). Also, connected via internet, VPN, colocated all make a difference. Brokers are trying to get volume business so they will provide more details than you might think.
VPS in Virginia to IB in Connecticut (as per IP location): ping ndc1.ibllc.com --- ndc1.ibllc.com ping statistics --- 16 packets transmitted, 16 received, 0% packet loss, time 15026ms rtt min/avg/max/mdev = 7.156/7.282/7.582/0.109 ms