# How to Speed Up Build Time ?¶

For projects using SCons or developers using build systems in IDEs (see the How to Configure my IDE ? section), it is possible to speed up the build time by parallelizing most of C++ compilations. This is usually done using the -j<CPU_COUNT> flag with SCons: For example

scons -j6


will use, when possible, $$6$$ concurrent compilations.

Warning

It is not recommended to set <CPU_COUNT> to a value superior to your number of processors. From a console, you can see yout number of processors by typing the following command line in a Python interpreter:

import multiprocessing
multiprocessing.cpu_count()


To avoid using the -j<CPU_COUNT> flag each time, you can type the following command line in your console:

cpu_count


This will automatically set the number of concurrent compilations to your number of processors minus one. You can manually specify the number of concurrent compilations using the --number <CPU_COUNT> flag.