in reply to After the OS upgrade the site responsiveness

I'd vote for both 'has improved' and 'hasn't changed appreciably'. Right now there are 42 users logged in. I just tried loading this page here several times and found that sometimes the page loads in less than 2 seconds, while at other times it takes about 7 seconds. SO it depends on how many users at hitting the site at the exact millisecond you send your request :)