Hi.
Sorry for inconvenience. The AVAST Firewall takes control over the MS Firewall due recommendation of Microsoft to register FW product to windows security center and do not use two or more same security tools at one time.
As you can imagine, when two firewalls inspect same traffic, it can cause some unwanted interactions and of course it has negative impact on the performance.
Unfortunately the Avast Firewall don't allow to control a traffic usage as you need. But, from my previous sentences, idea to use two or more firewalls is not recommended. If you are using different firewall product or MS firewall, you can remove the AVAST Firewall component and then you will be able to use mentioned tools by same way as you did that before the update.
All other parts of the AVAST will works as usual.
Problem with mettered connections and with reduce traffic in some circumstances is now discussed here in AVAST and may be solved in a future release of our product.
Hope this helps to you.