wds-sitemaps.php is timing out

…w/html/wp-content/plugins/wpmu-dev-seo/wds-files/wds-sitemaps/wds-sitemaps.php (64)
…w/html/wp-content/plugins/wpmu-dev-seo/wds-files/wds-sitemaps/wds-sitemaps.php (33)
…ww/html/wp-content/plugins/wpmu-dev-seo/wds-files/wds-sitemaps/wds-sitemaps.php(447) : runtime-created function (1)
in __lambda_func called at ? (?)

Hi, we've noticed that part of this plugin is slowing down the site as it runs out of memory. What's the recommended memory limit for PHP on a multisite install with BuddyPress and 1100 sites?

Thanks
Joss