Has anything radically changed? Frankly, an book g4 by its very nature is slow by modern standards, especially for browsing the web. We could get more information about the specifications of your particular ibook but it just isn't worth tossing too much money into a G4 these days. Once you take about more than a few tens of dollars it is better to save to invest in a better used model.
Get more information about your computer. Go to the Apple in the upper left corner of any window, then "About This Mac", then "More Info..." Copy and paste the information here, but omit the serial number and Hardware UUID (if present).
How much free/available space do you have on your hard drive? How much RAM do you have?
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