Use
.Xr ccache 1
for the build.
No configuration is required except to install the
.Sy devel/ccache
package.
When using with
.Xr distcc 1 ,
set
.Sy CCACHE_PREFIX=/usr/local/bin/distcc .
The default cache directory of
.Pa $HOME/.ccache
will be used, which can be overridden by setting
.Sy CCACHE_DIR .
The
.Sy CCACHE_COMPILERCHECK
option defaults to
.Sy content
when using the in-tree bootstrap compiler,
and
.Sy mtime
when using an external compiler.
The
.Sy CCACHE_CPP2
option is used for Clang but not GCC.
.Pp
Sharing a cache between multiple work directories requires using a layout
similar to
.Pa /some/prefix/src
.Pa /some/prefix/obj
and an environment such as:
.Bd -literal -offset indent
CCACHE_BASEDIR='${SRCTOP:H}' MAKEOBJDIRPREFIX='${SRCTOP:H}/obj'
.Ed
.Pp
See
.Xr ccache 1
for more configuration options.