I would not recommend changing your DNS settings to Google or Cloudflare. Google might have the fastest DNS settings but at a cost of privacy.
I have not given much thought to this problem, but I think if given a choice between Cloudflare and Google, I would rather opt for Cloudflare. The performance might be slightly better with Google's DNS settings but they will be tracking you, advertising to you like crazy, and you are just giving them more of your data to sell.
@UmerIdrees
I haven't experienced any issues with Bitcointalk today, but I remember seeing something similar in the past. It's usually solved rather quickly in my experience.