OnixS C++ FIX Engine  4.9.0
API Documentation
Understanding Send Latency

The overall latency of the OnixS::FIX::Session::send method includes all latencies of all operations inside this method. The following sequence of operations are performed when the OnixS::FIX::Session::send method is called:

Based on the above, one can understand what the send latency includes. However, there is another important aspect. The latency of OnixS::FIX::Session::send method (as any other function) depends on the period with which you call it. When you call a function infrequently, in this case, the function path and associated data structures will not be in a processor cache and this can increase the function latency. However, if you call a function frequently then you can avoid cache misses and keep the function path fast. For this purpose, there is the OnixS::FIX::Session::warmUp method, please see the Low Latency Best Practices page for details.