safari working really slow in loading arkworks and videos

Greetings,

If you're using Safari 4.0.3, then it could be the Top Sites and Cover Flow features that are slowing down the loading of content. Try this:

Quit Safari if it's running and open System Preferences>Network.
In the DNS Server tab, make sure IPv6 is turned off, and enter these two DNS servers to replace the ones you currently have:

208.67.222.222
208.67.220.220

click Apply Now and quit System Preferences.

Next, do these things in order:

1. Go to Home/Library/Cookies and delete the Cookies.plist file.
2. Go to Home/Library/Caches/com.apple.Safari and delete the contents of that folder.
3. Go to Home/Library/Caches/com.apple.Safari/Web Page Previews and delete the contents of that folder.
4. If you don't want to use the Top Sites feature, open Terminal and paste in this command:

defaults write com.apple.Safari DebugSnapshotsUpdatePolicy -int 2

then press Enter or Return, then quit Terminal.

5. Go to Home/Library/Caches/Metadata/Safari and delete the contents of that folder.
6. Go to Home/Library/Caches/Safari and delete the contents of that folder.
7. Go to Home/Library/Safari and delete these files (if you have them):

Downloads.plist
History.plist
Form Values
LastSession.plist
WebpageIcons.db

Then restart Safari and see if the speed is improved.

...or you could select all the items in the "Reset Safari" option that's in the "Safari" menu.

And you should reset you modem from time to time. There should be a small hole on the back of the modem where you can insert a paperclip reset it.