in top of the stat() syscalls from strace is /etc/mtab which is quite awkward for implementation which tries to be performant....

i suppose it's result can be cached somehow to improve the performance:

{{{

strace -ff /usr/bin/updatedb -f "$(< /proc/filesystems awk '$1 == "nodev" { print $2 }')" 2>&1 | grep -Eo 'stat("[^"]+' | sort | uniq -c | sort -nr | head -n10

28764 stat("/etc/mtab
8016 stat(".
1534 stat("CVS
222 stat("LC_MESSAGES
221 stat("images
171 stat("actions
159 stat("0
150 stat("lib
137 stat("META-INF
117 stat("src
}}}