An internet browser is usually speedy when you first open it, but after opening a few tabs and visiting your favorite websites over the course of a day, its performance may slow down.

If you have experienced this problem, you might try some of the suggestions from this article by Lifehacker, including:

• Uninstall unneccessary extensions and add-ons for Firefox and Chrome. Firefox has even created a special web page listing its slowest add-ons.
• Uninstall and re-install Flash and Java. Many websites are designing Flash-free versions of their sites, so you may be able to live without Flash. If you still want to use it, it's a good idea to stay updated to the latest version. For Java, try a tool like JavaRa to remove old and redundant versions from your computer.
• Clear your cache and browsing history. This is an old standard tip, but a necessary one for cleaning out the old data cluttering up your computer. Once it's all cleared, you might consider reducing the duration between automatic cleanings (for example, only save your history for a day instead of a week or month).
• Work with multiple browsers. Consider using Chrome for Flash-intensive sites and Firefox for other web browsing. Or try Opera or Safari and see if you have a speedier experience.

If your primary browser is Internet Explorer, first be sure you are using a newer version (either 8 or 9). Then, try this article from Microsoft for five ways to speed up IE.