What is the output switching frequency(Low-to-High & vice-versa) limit of GPIO pin for colibri V50?

I trying to generate the frequency using System.thread to call the method containing desired instructions to set the level of GPIO pin of VF50. I got acceptable result below 100Hz, but not for high frequencies(from 100Hz to 10kHz).

For generating higher frequencies a normal thread/gpio setup may not be best option.
Use available PWMs present on VF50 for better response.
If your application demands more real time performance then please consider Colibri VF61 as option which is having MCU core(Cortex M4) and can run RTOS like FreeRTOS
http://developer.toradex.com/knowledge-base/freertos-on-the-cortex-m4-of-a-colibri-vf61