turbo_mode is a build option that speeds up compile times significantly.
As the one-class-per-file convention is becoming more common in the project, compile times have become uncomfortably long. However, because the preferred code conventions also encourage keeping the global namespace clean, it is possible to merge multiple source files together and build them as one. This is much faster than compiling the files separately because the thousands of lines of C++ headers only need to be processed once.
The CMake option
DENG_ENABLE_TURBO can be used to enable or disable the source file merging. The option is enabled by default starting from build 2033.
There are a few details and caveats to be aware of:
staticsymbols should have unique names in the entire directory rather than just the single file.