The shield may result in wrong measures, the only way to measure correct is to download a biiiig file (one that take minutes to download) and time the download, the turn off shields and repeat
Unfortunately no difference (16GB file), Avast real f**k in 50% my bandwidth (including between PC’s on my home network) and i also tested in several internet speed test providers. Avast Firewall really cap my bandwidth. I tested with different Avast configs Private/Public network , HTTP/HTTPS on/off, reseted configd, reinstall Avast, you name it.
Only when i put Firewall Off i really have my full internet bandwidth.