Slowdowns are natural for any VPN because the signal needs to travel more - from you to the VPN server, and then to the data you request. The closer you are to the VPN server, the shorter is the way, and the lower is the speed loss. So please use the countries nearest to yours, and you will have the highest speed possible.
As for the new tab opening: we inform free users about our current promotions. Many value this as an opportunity to get our Premium service with a good discount. This happens once per promotion. To stop this information, you can turn on "Don't show promo offers" in the extension settings.