Website Speed up Issues

Hello all, i’m facing website speed loading issues. When i check on google insights and gtmatrix or on pingdom they show that my site is loading fastly. But google shows upto 10 seconds loading time in analytics report, i read some website speed up tips on website, they said to install plugins and i did that. But still facing problem, i’m worried about my website seo. So all of you its my request to help me. A screenshot is added, according to this website is taking 14 seconds to load. Thanks in advance.