What's the cause of GPU panics on macbook pro mid 2010?
Suggested problem tracing /and repair) steps (after each test the performances).

Some applications will force use the Nvidia card (without automatic switching).

Yes the ZOOM feature adds stress to the GPU.


Vacuum clean the inside of your Mac to improve cooling.
Google and Install gfxCardStatus, Leave on Dynamic Switching. From there it will Monitor and Alert you to what apps switch you to the Nvidia Graphic Card.
Also open the Activity monitor - Energy tab, where you can see when the Nvida card kicks in, and does it switch on/off irregularly.
Monitor your Console log for irregular (fast)GPU switching.
Do some hardware testing: 



  GpuTest is a cross-platform (Windows, Linux and Max OS X) GPU stress
  test and OpenGL benchmark. GpuTest comes with several GPU tests
  including some popular ones from Windows'world (FurMark or TessMark).



worst case remove the Nvidia card, and go without it.