Try Firefox, it's usually faster…
But very resource hungry, so it'll probably make things worse.
Are you running other applications at the same time? Have you installed extra RAM, or are you on the same amount it came with?
Using Activity Monitor, as suggested, may help you find where the problem lies. I discovered that Safari can use loads of RAM, especially if you have several tabs/windows open in Safari. A programme called 'Flash Player(Safari Internet plug-in) also uses up loads.
If the spinning wheel/beachball spins for a while then stops, and allows you to continue browsing, then it's possibly just a RAM issue (not enough to run the programmes you have open, without stalling).
Could also be an internet issue, if other programmes aren't affected.