A new version of the Firefox Web browser is scheduled for release Tuesday with improvements in security, speed and design. Many of the enhancements in Firefox 3 involve bookmarks. The new version lets Web surfers add keywords, or tags, to sort bookmarks by topic. A new “Places” feature lets users quickly access sites they recently bookmarked or tagged and pages they visit frequently but haven’t bookmarked. There’s also a new star button for easily adding sites to your bookmark list — similar to what’s already available on Microsoft’s Internet Explorer 7 browser.