WordPress Hostgator Extremely Slow website Fast Admin

In Short, the problem is our website is extremely slow, taking around 40-60 S to load each page.

Here’s the story :

We are building an ecommerce website on wordpress. The test server is of Amazon and the website was hosted on VPS server of godaddy. It used to take 15 s to load on VPS whereas amazon server was taking around 7-8 S. We wanted to bring it down to less than 3 S per page. As the VPS server was slow, we shifted it to dedicated server of hostgator.

The change resulted in positives like pagespeed score on pingdom tools increased above 90, it was 60 on amazon test server and godaddy VPS earlier. As per google pagespeed results, the new server is excellent and has waiting time of less than 0.4 S. For VPS godaddy it used to be 5 S and amazon it is 2 S.

Here’s the problem : Surprisingly, the time for the pages to load has increased to 50S – 60 S now. It is observed that main issue is the wait time per request.

Other pointers :

1) The admin panel is opening pretty quickly (less than 5 S) and it is easy to access. So issue is only with rest of the site not with admin.
2) If we remove the theme then website becomes faster and with theme, website becomes slower on the hostgator server. Now, one would say that problem must be in the theme. But same theme was giving much better loading times earlier as stated above. Now, with a better server, it should give same times if not better.
3) Time to load first byte was always the problem. It has always been around 50% of total load time for the page. e.g. 7-8 S for go daddy, 2-3 S for amazon and currently 30 S for hostgator. So, i know it is a problem but nothing new in it. 60 S load time on dedicated server is unbelievable and I am not able to locate where and what is going wrong.

Please help !