The error.log on the demo is full of errors causing the server to slow down.
4447- Warning:</strong> <i>imagecreatetruecolor() [<a href=&<a href='/039'>#039</a>;function.imagecreatetruecolor&<a href='/039'>#039</a>;>function.imagecreatetruecolor</a>]: Invalid image dimensions</i> in <b>/home/piwik/www/demo.piwik.org/libs/pChart2.1.3/class/pImage.class.php</b> on line <b>93</b>
4723-<br /><br />Backtrace --><div style="font-family:Courier;font-size:10pt"><br />
4806-<a href='/0'>#0</a> Piwik_ErrorHandler(...) called at [:]<br />
4854-<a href='/1'>#1</a> imagecreatetruecolor(...) called at [/home/piwik/www/demo.piwik.org/libs/pChart2.1.3/class/pImage.class.php:93]<br />
4976-<a href='/2'>#2</a> pImage->pImage(...) called at [/home/piwik/www/demo.piwik.org/plugins/ImageGraph/StaticGraph.php:244]<br />
5091-<a href='/3'>#3</a> Piwik_ImageGraph_StaticGraph->initpImage(...) called at [/home/piwik/www/demo.piwik.org/plugins/ImageGraph/StaticGraph.php:264]<br />
5232-<a href='/4'>#4</a> Piwik_ImageGraph_StaticGraph->getTextWidthHeight(...) called at [/home/piwik/www/demo.piwik.org/plugins/ImageGraph/StaticGraph/Exception.php:39]<br />
5390-<a href='/5'>#5</a> Piwik_ImageGraph_StaticGraph_Exception->renderGraph(...) called at [/home/piwik/www/demo.piwik.org/plugins/ImageGraph/API.php:522]<br />
5534-<a href='/6'>#6</a> Piwik_ImageGraph_API->get(...) called at [:]<br />
5592-<a href='/7'>#7</a> call_user_func_array(...) called at [/home/piwik/www/demo.piwik.org/core/API/Proxy.php:190]<br />
5694-<a href='/8'>#8</a> Piwik_API_Proxy->call(...) called at [/home/piwik/www/demo.piwik.org/core/API/Request.php:128]<br />
5802-<a href='/9'>#9</a> Piwik_API_Request->process(...) called at [/home/piwik/www/demo.piwik.org/plugins/API/Controller.php:27]<br />
5920-<a href='/10'>#10</a> Piwik_API_Controller->index(...) called at [:]<br />
5981-<a href='/11'>#11</a> call_user_func_array(...) called at [/home/piwik/www/demo.piwik.org/core/FrontController.php:138]<br />
6090-<a href='/12'>#12</a> Piwik_FrontController->dispatch(...) called at [/home/piwik/www/demo.piwik.org/index.php:53]</div><br />
6203- </pre></div><br />
Another error is
4447- Warning:</strong> <i>imagecreatetruecolor() [<a href=&<a href='/039'>#039</a>;function.imagecreatetruecolor&<a href='/039'>#039</a>;>function.imagecreatetruecolor</a>]: Invalid image dimensions</i> in <b>/home/piwik/www/demo.piwik.org/libs/pChart2.1.3/class/pImage.class.php</b> on line <b>93</b>
4723-<br /><br />Backtrace --><div style="font-family:Courier;font-size:10pt"><br />
4806-<a href='/0'>#0</a> Piwik_ErrorHandler(...) called at [:]<br />
4854-<a href='/1'>#1</a> imagecreatetruecolor(...) called at [/home/piwik/www/demo.piwik.org/libs/pChart2.1.3/class/pImage.class.php:93]<br />
4976-<a href='/2'>#2</a> pImage->pImage(...) called at [/home/piwik/www/demo.piwik.org/plugins/ImageGraph/StaticGraph.php:244]<br />
5091-<a href='/3'>#3</a> Piwik_ImageGraph_StaticGraph->initpImage(...) called at [/home/piwik/www/demo.piwik.org/plugins/ImageGraph/StaticGraph.php:264]<br />
5232-<a href='/4'>#4</a> Piwik_ImageGraph_StaticGraph->getTextWidthHeight(...) called at [/home/piwik/www/demo.piwik.org/plugins/ImageGraph/StaticGraph/Exception.php:39]<br />
5390-<a href='/5'>#5</a> Piwik_ImageGraph_StaticGraph_Exception->renderGraph(...) called at [/home/piwik/www/demo.piwik.org/plugins/ImageGraph/API.php:522]<br />
5534-<a href='/6'>#6</a> Piwik_ImageGraph_API->get(...) called at [:]<br />
5592-<a href='/7'>#7</a> call_user_func_array(...) called at [/home/piwik/www/demo.piwik.org/core/API/Proxy.php:190]<br />
5694-<a href='/8'>#8</a> Piwik_API_Proxy->call(...) called at [/home/piwik/www/demo.piwik.org/core/API/Request.php:128]<br />
5802-<a href='/9'>#9</a> Piwik_API_Request->process(...) called at [/home/piwik/www/demo.piwik.org/plugins/API/Controller.php:27]<br />
5920-<a href='/10'>#10</a> Piwik_API_Controller->index(...) called at [:]<br />
5981-<a href='/11'>#11</a> call_user_func_array(...) called at [/home/piwik/www/demo.piwik.org/core/FrontController.php:138]<br />
6090-<a href='/12'>#12</a> Piwik_FrontController->dispatch(...) called at [/home/piwik/www/demo.piwik.org/index.php:53]</div><br />
6203- </pre></div><br />
It would be great to resolve these issues since they can cause performance issue on the demo.