ClickHeat is a visual heatmap of clicks on a HTML page, showing hot and cold click zones. This plugin based on [Dugwood's ClickHeat version 1.14](https://github.com/dugwood/clickheat). It is an OpenSource software, released under GPL licence, and free of charge.
This plugin doesn't consider the IIS. Sorry. And please delete the ClickHeat plugin (yourpiwik/plugins/ClickHeat) manually via FTP or Explorer. We are waiting patches for IIS.
This plugin uses minimal text to record data and file based logging. And when click.php is called from a special Javascript for cgi, just append text on end of the each file. And when you analyze the click data and make a heatmap, plugin will create cached heatmap as png image file.
Therefore, we expect the plugin light works, but we don't know what load it has under Piwik 2.x. So we are very glad, when you inform us about your situation.
Please see the link [Performance and optimization](http://www.labsmedia.com/clickheat/156894.html) about system resources. If you want performance, you need to avoid to use a cgi, that is possible. It method is explained on the link.
Plugin places heatmap images in the cache directory: yourpiwik/tmp/cache/clickheat/cache. Therefore when you suddenly met with such probrem, you can delete cache files, but __do not delete cache directory__.
Check that your website does not set the HTTP header __X-FRAME-OPTIONS__ to __SAMEORIGIN__ as this will prevent this plugin from iframing your website for the heatmap report. Please see [Page Overlay Troubleshooting](http://piwik.org/docs/page-overlay/#page-overlay-troubleshooting), that is same problem.