All of the pages on my website are loading within 2-4 secs with the exception of one page (the login page).
For some reason the TTFB is aprox 30 secs.
It is a WordPress site hosted on an AWS EC2 micro instance with Cloudfront CDN.
When I check the pages on pingdom they average 2-4 secs with the exception of this page:
Is there any way of working out why it is so slow and fixing it?
Running it through Pingdom shows that it's waiting 30s for a server response, so you need to start looking at your DB queries. I'd recommend two plugins for this: Query Monitor and Debug Bar. If you install these, they will reveal which particular queries are taking a long time to execute. Once you know what you're looking for, you can then start to figure out how to alleviate your problems.