Slow Internet Browsing: Takes 30 Seconds To Load A Page?

i just bought this new computer for 1 of the staff and i have configured his profile. but then i tried to browse the internet and found it very slow, not in opening the IE, but in loading the pages. it takes around 20 to 30 seconds to load a page. when i use ping to check the connectivity, it takes a long time to display the first line, but it gives me a 1ms when pinging the server, which is good.

now i login with the administrator account and find the internet browsing is fast, but again the ping takes a while to display the first line. i did give that user Administrator permissions and tried again, but it's the same issue. i thought it would be higher permissions which could affect the user. So, i added the user to "domain admins", "administrators" groups, and i tried again, but the same situation