I originally posted this to a discussion thread about this problem but thought it might get more attention as a support request.
I have a problem with selection being very slow on a Thinkpad X220 with "Intel(R) Sandybridge Mobile (GT2+)" (according to my Xorg.0.log), running Ubuntu 13.04. Meshlab works fine until I try to select a region by clicking and dragging. Even if the region doesn't intersect with any polygons, the framerate drops to <0.5fps. If I am patient and wait for the display to update before releasing the drag, the selection does eventually work but it is unusably slow.
For some other work I have installed a Windows 7 virtual machine running in VMWare. I installed Meshlab in the virtual machine as a test, and selection works comparatively great. The program generally runs at a slightly slower frame-rate than on Ubuntu, but region selections are no slower than any other operation. On the whole it is much more useable.
I figured this is because in VMWare, the graphics is entirely software rendered, avoiding some kind of 3D acceleration problem, so I tried running Meshlab in Ubuntu with various options to disable 3D acceleration. I have tried running with the environment variables LIBGL_ALWAYS_INDIRECT=1 LIBGL_ALWAYS_SOFTWARE=1, and also by disabling hardware acceleration using DriConf (~/.drirc), but none of these options get anywhere near the performance of the VMWare version when selecting.
Any ideas? I also tried running Meshlab inside Xnest, to force software rendering, but then it doesn't work at all ;)
If it helps any developers, I just attached ltrace to Meshlab just as I was doing a select, and I've posted the summary (-c) here: http://pastebin.com/yQJUhaZv it looks like the culprit might be something in Qt?
Had this issue as well on Linux Mint 16 Petra. Your hint was really useful, as I fixed my issue. Basically, my laptop is using Optimus (2x Graphics Cards: Intel and nVidia) and I got it working on my laptop using bumblebee. That means that if I want to start an application on the nVidia GPU I have to say
optirun ./executable. Set the defaults for meshlab starting asoptirun meshlab whatever.plyand it worked. I believe the Intel GPU is quite slow.The workaround is to disable GPU computation and do it all on CPU (not sure how), but if you have bumblebee, I see no reason for doing that.
Contributing to this 3 year old topic as it is the first result on Google.