(Version originale en français)
I very frequently compile Linux kernels, often during training sessions or engineering services (mainly in the field of embedded systems or drivers development), sometimes while writing articles or books.
Compilation time varies greatly depending on the amount of code (drivers, filesystems, protocols, etc.) and on the CPU power of the host machine. On a mid-range PC, compiling a kernel adjusted for an embedded system (with very few drivers) lasts about three minutes. On an entry level machine (or a little old one), compiling a generic kernel for PC (with hundreds of drivers as modules) can last an hour.