This is using the off-the-shelf packages for pcl and ros in Kinetic with Ubuntu 16.04 and Jade with 14.04.

I made this package which is mostly http://pointclouds.org/documentation/tutorials/pcl_visualizer.php with ros subscribers providing the point clouds, and embedding into a qt window:

https://github.com/lucasw/rqt_pcl_visualizer

What I see is that in Jade it works exactly as expected (last I checked a few commits ago), but in Kinetic when I move the mouse to rotate the view it big fraction of a second to register, and incoming point clouds don't show up until seconds later.

It's likely this is the fault of qvtk in qt5 and nothing to do with ros or rqt at all, but maybe others here have insight from having made the same migration:

ui_.qvtk_widget->SetRenderWindow(viewer_->getRenderWindow());
viewer_->setupInteractor(ui_.qvtk_widget->GetInteractor(), ui_.qvtk_widget->GetRenderWindow());

The ui file defines the qvtk widget:

<widget class="QVTKWidget" name="qvtk_widget"/>

Maybe this is related:

http://vtk.1045678.n5.nabble.com/QVTKWidget-rendering-performance-td5730642.html