Safari on OS X Yosemite 10.10.4 CPU problem
I found a way to reset my Safari installation this way:

1) I created a backup of my bookmarks:

cp ~/Library/Safari/Bookmarks.plist ~/Desktop/


2) I deleted some Safari specific files:

rm -rf ~/Library/Caches/com.apple.Safari \
       ~/Library/Caches/com.apple.Safari.SearchHelper \
       ~/Library/Caches/Metadata/Safari \
       ~/Library/Cookies/Cookies.binarycookies \
       ~/Library/Cookies/Cookies.plist \
       ~/Library/Preferences/com.apple.Safari.plist \
       ~/Library/Preferences/com.apple.Safari.Extensions.plist \
       ~/Library/Preferences/com.apple.Safari.LSSharedFileList.plist \
       ~/Library/Preferences/com.apple.Safari.RSS.plist \
       ~/Library/PubSub/Database \
       ~/Library/Safari


3) Then I restored my bookmarks:

mkdir ~/Library/Safari &amp;&amp; mv ~/Desktop/Bookmarks.plist ~/Library/Safari/Bookmarks.plist


Now the CPU and the fan stay calm.