Directory listing taking up to 30 seconds to respond

I'm having intermittent issues with my website, and when it's not responding there seems to be an issue with performing a directory listing on the host e.g. I performed an ls -l and it took over 30 seconds to return:
e.g.
time ls -l www > /dev/null

real 0m33.688s
user 0m0.004s
sys 0m0.000s

You can see below that it's not a particularly large folder, has anyone come across something like this before and had it fixed? Or is it an issue with the host the my site is on?

Thanks!
[details="listing summary"]
index.html.ovh.old
license.txt
wp-activate.php
wp-blog-header.php
wp-config.php
wp-content
wp-includes
wp-load.php
wp-mail.php
wp-signup.php
xmlrpc.php
index.php
readme.html
wp-admin
wp-comments-post.php
wp-config-sample.php
wp-cron.php
wp-links-opml.php
wp-login.php
wp-settings.php
wp-trackback.php
[/details]