First, I’m an Avast user and not an Avast Team member and I don’t use a VPN.
However there is going to be an overhead with the routing of your request and the return, some sites actively try to prevent VPN, security/restricted content, etc.
You can try using split tunnelling (not even sure if this is available on the Avast SecureLine VPN or not.
This is a search on using split tunnelling,
And