Check out the headless rendering option: EGL support is available in Ignition Fortress . Also see my comment in that thread for workarounds if you need to run a version of Gazebo that does not support the headless rendering.
Running speed on integrated GPU really depends on the complexity of the world you use and the number, resolution and FPS of rendering sensors in your simulation. Usually, iGPUs run very low on RAM, which causes constant moving of data between CPU and GPU. If the BIOS of your computer allows setting a larger piece of RAM dedicated to the GPU, set the maximum.