The current default Qt version is 4.7.4 (at least on Windows). We did try to update to 4.8.x last year, but there were some (at least one rather nasty which halved the performance on Windows when running a heavy scene) regressions issues. Try to update to the latest series Qt4.
Did some preliminary tests with Qt 4.8.4 and VC10-built Meshmoon Rocket and the Arcala scene seemed to run fine at steady 60 FPS, and 75 FPS with frame limiting disabled on my rather beefy work PC.
The current default Qt version is 4.7.4 (at least on Windows). We did try to update to 4.8.x last year, but there were some (at least one rather nasty which halved the performance on Windows when running a heavy scene) regressions issues. Try to update to the latest series Qt4.