Woah! Are you sure you're getting this big hit? Because, that's a huge difference- almost 98% reduction! And I have used Air VPN too, and I think it's a good VPN. Besides, it's an understood thing that when you'll use a VPN, you will face a bit of reduction, as it's explained briefly in this article of Ivacy VPN: https://support.ivacy.com/kb/how-to-turbo-charge-your-vpn-speed-2/
Moreover, I have used many VPNs and have also discussed about their pros and cons in different articles, but I found these VPNs to be really good in terms of speed, encryption and customer support: Ivacy VPN, Express VPN, Tunnel Bear and VyprVPN.
So, that's my response to your question. If anyone have any more questions regarding VPNs, feel free to ask me.