The real speed of loading web site

[sweb]

Hi all,
I know that it takes time to speed up site load ... and I have invested some time on this issue.
A few days ago my friend recommended the site to test
http://www.webpagetest.org

and to do a comparison. Incredibly, his load of 1.5 seconds and my site by 7.8 seconds. I took pictures, cleaned up code, CSS, and the same is repeated in the result. What could be a problem. He told me that my hosting is not good quality. Is that correct, and what else do I need to obat attention? I would like to keep my slider, but if it is a problem I will find another solution...Test my site is located at:http://www.webpagetest.org/result/120125_6W_3027R/1/details/

Any small suggestions will help me a lot

Thanks!