Slow response on WPMU DEV Hosted site.

I am getting good speed scores on Google insights and gtmetrix, but Pingdom is showing more detail. I am not sure what it is related to. I have more than a 15 second page load time on Pingdom but on gtmetrix it is less than 3. The first-byte response is taking all the time. https://monosnap.com/file/WXueFCjI1LQjOLctMBKKk1lZdbCRHa

Please check and help.