So the server is slow:
Roll back to the previous known working build - Success? Code problem - Fail? Go on.
Ping ip address - Success? maybe a DNS problem, go on. - Fail? Server or connection problem, go on.
Ping and tracert your domain.com from inside your network - previous success - fail: DNS problem - success? go on. - previous fail and: - Fail? Go on, could be you or network. - Success? Go on.
Try it from outside your network (http://centralops.net/co/) - Fail? The server's network connection sucks. - Success? If inside network was fail, your network sucks.
Check the server load: CPU/RAM usage. Is it overloaded? - Yes. Who's the culprit? Kill some processes/reboot. - No? Go on.
what other steps should i add?