Checked the page loades, also checked the website speed using page speed checker but it is normal. Server CPU usage is normal, may be huge traffic is causing the slowness.
Will check the theme coding again, if any hard coded element is there then i will remove that.
we have just made some minor changes to the tabs on the index page. now the tabs width increased to match the table size and the height reduced a little to make it compact. also the top edges made to look round with curved edges.