What are the tools available to monitor which resources (CSS,JS, image) took what time to download in safari browser. it could be a plugin like firebug, or an independent tool that can sniff the browser traffic and monitor them
You can also use Safari's built-in tools. In the preferences, open "advanced" and check the "enable developer tools" checkbox. Then load a web page and choose "Develop" from the menu bar. I like for example the Web Inspector view.