The reason for the dramatic slowdown of the ROM state filter with Qt 4.3.2 has meanwhile been found. It’s a performance issue of Qt 4.3.2 and Trolltech is working on it.

There has been some correspondence with the responsible Qt developer. He is aware of the problem and working hard to fix it (I’ve seen other trouble reports as well). Trolltech will improve their performance testing to minimize the risk of such issues in the future.

As a short-term workaround – even though it’s a bit risky, because it can cause crashes (I’ve not seen it crashing, though – is to change src/gui/itemviews/qtreeview.cpp in the Qt source tree and comment out line 545 (“// d->executePostedLayout();”). Rebuild Qt and have fun !