optimized the speed

git-svn-id: https://plugins.svn.wordpress.org/squirrly-seo/trunk@938512 b8457f37-d9ea-0310-8a92-e5e31aec5664
fixed small bugs in performance analytics page

git-svn-id: https://plugins.svn.wordpress.org/squirrly-seo/trunk@938521 b8457f37-d9ea-0310-8a92-e5e31aec5664