Website/Page Load Speed is Fluctuating

Hi Guys,

Got some really big issue regarding the stability of my website loading speed. There are times that it loads so fast, and there are times that it loads so slow, like about 15-20 seconds.

Also, there are certain pages that really loads so slow even though the only content on that page is just text (no image).

By the way, my website is http://www.ntrust.com.sg

The old version was PHP and transferred to WordPress. After the transition, I got this website/page load speed fluctuating already.

I badly need your expert thoughts and advice on this.

Thank you so much!

Cheers!