Bug in MS Reporting

Not sure it is a feature because it looks too buggy. In case of using hiding rule for a table element, Interactive Height rule does not work for that report. At a first glance it is not a big problem, but if the report must be built on a huge dataset, it takes too much time to render huge HTML, transfer it to a client and render it in a browser. In my case a report built on ~1 000 000 records was displayed at client in about 10 minutes in IE. After the hiding rule was removed the report was displayed in a few seconds.