Good article talking about what latency really is and what to think about when trying to measure true end-to-end latency in the trading process. I think for the top end of the market the only way to reduce latency further is through hardware. My quote:
When evaluating latency, it’s vital to consider all of the contributing factors, including the trade logic (the code that runs matching engines and algorithms), the speed of calculation hardware, the speed of telecom switch hardware, the quality and number of connections, and the distance between network nodes, according to Kevin McPartland, analyst at TABB Group. The industry as a whole is rapidly approaching the point where, “The code is so tight, hardware improvements are the main thing that will increase the overall efficiency of the operation,” McPartland says.