VPN slow internet speed

Hi
when I've added the VPN to my iphone the internet down load speed goes from 50mb to 18mb and the upload speed goes from 18mg to 1mg.
Why does this happen please and what can I do to maintain optimal speed at all times ?
thanx
Joan

Hello Joan,
Thank you for contacting AVG Community Support.
We are really sorry to know this. We'll certainly check and help you out.
I understand your concerns regarding the drop in the Internet speed after turning on the VPN.
You may experience a slower internet connection when using VPN. This is because a VPN encrypts traffic and data before sending it to a server. Depending on the distance and capacity of the server, this process may cause a slightly slower, but safer, internet connection.
I understand you would like to maintain optimal speeds. To help with this, please let us know about your VPN subscription.
Please let us know whether you connect VPN via AVG Antivirus or via AVG Secure VPN app.
Thank you and keep us updated.

Thankyou for your reply.
My internet connection is certainly safer as I'm unable to use it with the added VPN.
I'm unsure how to answer your question as don't know whether I'm connected via AVG antivirus or via AVG secure.  Please instruct me where to look on my device to be able to answer this question.  
thankyou

Hi Joan,
Thank you for the reply. I see you are not sure whether it is connected Via AVG AntiVirus or AVG Secure VPN. No worries, We will definitely help you. Could you please share us the screenshot of the page (https://support.avg.com/SupportArticleView?urlname=AVG-Create-screenshot)? which has a programs installed in your PC. You can post the screenshot here in your topic. Click on Answer & then click on the Image [mountain symbol] & follow the instructions. Thanks in advance.

Hello Joan,
Thank you for contacting AVG Community Support.
We are really sorry to know this. We'll certainly check and help you out.
I understand your concerns regarding the drop in the Internet speed after turning on the VPN.
You may experience a slower internet connection when using VPN. This is because a VPN encrypts traffic and data before sending it to a server. Depending on the distance and capacity of the server, this process may cause a slightly slower, but safer, internet connection.
I understand you would like to maintain optimal speeds. To help with this, please let us know about your VPN subscription.
Please let us know whether you connect VPN via AVG Antivirus or via AVG Secure VPN app.
Thank you and keep us updated.