Trade Net X reimplements parts of the game's "Trade Net" module to improve performance. More specifically, it accelerates the process of computing road networks and sea trade connections by (1) gathering the needed map data into a cache-efficient container, (2) cutting out unneeded logic, and most importantly (3) reusing results across calls to the pathfinder. The speed up from Trade Net X can be very significant. In extreme cases (maximum size map, late game, many wars) it can reduce turn times by 90%.

Trade Net X is contained in its own DLL so it can be optimized by a compiler. The rest of C3X is implemented as a "C script", written in C but compiled only when the mod is installed. It's compiled using TCC which is a very small and fast compiler but comes with the tradeoff that it doesn't optimize the code it produces. Using TCC to compile Trade Net X would leave a lot of performance on the table, so instead it's compiled ahead of time using MSVC (Microsoft's C++ compiler). Source code is included so you can compile it yourself if you want. To do so, you would need to install the Windows SDK (available from MS for free) then run BUILD.bat from within the x64_x86 Cross Tools Command Prompt.