are you building in parallel (Using all your CPU cores)? Add the line in red to your /etc/sbopkg/sbopkg.conf
Code:
DIFF=${DIFF:-diff}
DIFFOPTS=${DIFFOPTS:--u}
RSYNCFLAGS="${RSYNCFLAGS:---verbose --timeout=30}"
WGETFLAGS="${WGETFLAGS:--c --progress=bar:force --timeout=30 --tries=5}"
export MAKEFLAGS="j $(expr $(nproc) + 1)"