Why is my Website Opening Very Slowly?

It took me 4 seconds for the server to respond and then 10 more seconds to load all of the resources that your page serves.

Are you saying you suddenly had an issue? What exactly do you mean by slowly?

I mean ; I tested with pingdom and it gets so slow opening times.
I got this issue after the update of my theme.

It took you 14 seconds for opening; thats too much of it.
Could you suggest me which resources should I remove from the site?

Try deactivating your plugins and testing again to explore how long they take. When they’re all deactivated, try switching to the Twenty Fourteen/ Fifteen theme to explore whether you have loading issues with your current theme.

According to Pingdom your home page is 2.3mb in size. Try reducing the number of requests: is everything being loaded necessary? do you need every plugin? Probably only you can judge that: go through the list in Pingdom.

If you’re not already doing it, set up caching.