Zoho CRM has become bery slow even freezing the browser window while calling up menu functions

Zoho CRM has become bery slow even freezing the browser window while calling up menu functions

Very bad when trying to customize a report that almost certainly freezes the window. We are using Chrome and Firefox in most recent versions and both seems to have the same result. Other online apps such as GMail are not affected so Internet is not the issue. Can you please review and help this out. This issue is dragging on for weeks and exhausting us by the day.
Many thanks! 

.silvio