Along with OS X 10.7.4, Apple also released Safari 5.1.7. The latest Safari update includes several general improvements and bug fixes.
The update also includes a new way of handling Adobe Flash on the web. If an older version of Flash attempts to run in Safari 5.1.7, Apple’s browser will automatically disable it and give you the option to install the newest version of Flash from Adobe’s website.
Following is the release Apple issued for Lion users:
Safari 5.1.7 contains improvements to performance, stability, compatibility, and security, including changes that:
*Improve the browser’s responsiveness when the system is low on memory
*Fix an issue that could prevent webpages from responding after using a pinch to zoom gesture
*Fix an issue that could affect websites using forms to authenticate users
*Disable versions of Adobe Flash Player that do not include the latest security updates and provide the option to get the current version from Adobe’s website.
Windows users running the latest Safari should also see improvement in browser responsiveness. The issue relating to web form authentication has also been fixed.
Safari 5.1.7 can be downloaded directly from Apple’s website or via Software Update.
Source: Cult Of Mac