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What Mac do you have?
What OS version do you have?
Does this happen for any web site, or just the same few you always use?
 
MacBook Pro late 2013 8/256gb. Last OS X version and last safari version. But it happens almost from the beginning of the use os x capitan. It happenes on all website :(
 
You could try restoring the default prefs for Safari. Get out of Safari. Hold down Option and click the Go menu. Select Library. Now open the preferences folder. Find the file com.apple.safari.plist and put it in the Trash. Now open Safari. This will create a new plist for it.

If that doesn't fix it in your main account, don't waste any more time looking for the culprit. Migrate to a new account.
 
You could try restoring the default prefs for Safari. Get out of Safari. Hold down Option and click the Go menu. Select Library. Now open the preferences folder. Find the file com.apple.safari.plist and put it in the Trash. Now open Safari. This will create a new plist for it.

If that doesn't fix it in your main account, don't waste any more time looking for the culprit. Migrate to a new account.
Don't work
 
Subject to do the closing. After upgrading the kernel, it's ok.
 
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