Apple has updated Safari and Keynote to improve performance:
Safari
This update contains various improvements, including fixes that:
-Improve stability
-Address issues that could cause hangs and excessive memory usage
-Address issues that could cause webpages to flash white
-Allow PDFs to be displayed within web content
Keynote
This update addresses issues when working with large Keynote presentations on OS X Lion. It also includes improvements in stability and accessibility for Keynote.
This update is recommended for users of Keynote 5.1. For detailed information on this update and individual application changes, please visit this site: http://support.apple.com/kb/HT5026.