Is there any way I can default avatar size? all the avatar sizes are really big, I tried many different plugins and they don't work.
Don't forget that the same avatar file is used on dozens of places in your forum, for example in your profile page it should be 150x150. So, wpForo crops to the max size 150x150px and uses it for avatars from 25px to 150px sizes. If you make them small, your profile page avatar will be inappropriate.
do you know how I could improve serve scaled images, they slow down my website _gtmetrix