had to disable update status module!

Brand new installation (4 hours ago).
The site was extremely slow for all admin pages (60-90 seconds page load) after installation

This would trigger an email from the server firewall:
Suspicious process running under user [name]
Executable: /usr/bin/php
Command Line (often faked in exploits): /usr/bin/php /home/[name]/public_html/index.php
Network connections by the process (if any): tcp: 213.175.xxx.xxx:36711 -> 140.211.xxx.xxx:80
Files open by the process (if any): /dev/urandom

Between every 1-7 minutes since installation, an error was logged in the drupal 'reports' section:
"Unable to fetch any information about available new releases and updates"

I notice that of at least the last seven days on one of my other sites on a different server, I have
had the same error message every cron run, although the site didn't seem to be affected by slowdown.

I switched off the update status module, and now the admin pages load correctly.

Does anyone have any ideas what is going on?