Banchmarking or knowing device performance (for shaders)?

Is there an easy way to benchmark or otherwise know the shader performance of a device?

I like to use some openGL shaders for background animations only if the device is fast enough and fall back to just a static background image if it isn’t.

Currently I use a shader in the title screen and measure the FPS. But that isn’t very reliable and doesn’t look very good. Is there an easier way to determine or know in advance the performance of a device?