Debug slow connection (from http://askubuntu.com/questions/147377/how-to-debug-slow-browsing-speed), use in the following way: curl -w "@curl-timing.cfg" -o /dev/null -s http://www.google.com/

curl-timing.cfg

\n
      DNS lookup                          :  %{time_namelookup}\n
      Connect to server (TCP)             :  %{time_connect}\n
      Connect to server (HTTP/S)          :  %{time_appconnect}\n
      Time from start until transfer began:  %{time_pretransfer}\n
      Time for redirection (if any)       :  %{time_redirect}\n
      Total time before transfer started  :  %{time_starttransfer}\n
\n
             Total time                   :  %{time_total}\n
             Size of download (bytes)     :  %{size_download}\n
             Average d/l speed (bytes/s)  :  %{speed_download}\n
\n