With NVIDIA control panel I switched Firefox to use integrated Intel. Firefox hung 40.0a1 (2015-04-09) Adapter Description Intel(R) HD Graphics Family Adapter Description (GPU #2) NVIDIA Quadro 1000M Adapter Drivers igdumd64 igd10umd64 igd10umd64 igdumdx32 igd10umd32 igd10umd32 Adapter Drivers (GPU #2) nvd3dumx,nvwgf2umx,nvwgf2umx nvd3dum,nvwgf2um,nvwgf2um Adapter RAM Unknown Adapter RAM (GPU #2) 2048 Asynchronous Pan/Zoom none ClearType Parameters Gamma: 2200 Pixel Structure: R ClearType Level: 100 Enhanced Contrast: 400 Device ID 0x0126 Device ID (GPU #2) 0x0dfa Direct2D Enabled true DirectWrite Enabled true (6.2.9200.16492) Driver Date 9-26-2011 Driver Date (GPU #2) 2-4-2015 Driver Version 8.15.10.2538 Driver Version (GPU #2) 9.18.13.4520 GPU #2 Active false GPU Accelerated Windows 2/2 Direct3D 11 (OMTC) Subsys ID 21d117aa Subsys ID (GPU #2) 21d117aa Vendor ID 0x8086 Vendor ID (GPU #2) 0x10de WebGL Renderer Google Inc. -- ANGLE (Intel(R) HD Graphics Family Direct3D9Ex vs_3_0 ps_3_0) windowLayerManagerRemote true AzureCanvasBackend direct2d 1.1 AzureContentBackend direct2d 1.1 AzureFallbackCanvasBackend cairo AzureSkiaAccelerated 0

https://communities.intel.com/thread/60104 Your Intel graphics driver is very old, try updating to the latest 9.17.10.4101 driver.

I'd also be interested to hear if it happens if you update to a 350.* level Nvidia driver.

I updated a while ago to Active No Description NVIDIA Quadro 1000M Vendor ID 0x10de Device ID 0x0dfa Driver Version 10.18.13.5382 Driver Date 8-7-2015 Drivers nvd3dumx,nvwgf2umx,nvwgf2umx nvd3dum,nvwgf2um,nvwgf2um Subsys ID 21d117aa RAM 2048 I still need to retest