Vk Download Speed

I updated my Mac to Sierra and also updated my SaveFrom Safari helper to 6.85. I've been seeing horrible download speeds ever since. For a 1 GB video, the download time is ever changing going up to 1 day or 16 hours if I'm lucky. I troubleshoot my Mac Sierra wifi problem and it didn't solve anything. It's still able to download a 1 GB video from Youtube though. Do you think this is Vk's fault?