To reproduce this:

1. Download Apache NetBeans 11.2

2. Run it with the latest build of lanai with the metal pipeline enabled:

$ export JAVA_HOME=.../lanai/build/macosx-x64/images/jdk
$ _JAVA_OPTIONS="-Dsun.java2d.metal=true" "/Applications/NetBeans/Apache NetBeans 11.2.app/Contents/Resources/NetBeans/netbeans/bin/netbeans" --jdkhome $JAVA_HOME

3. Create a new Java Application project (I used "Java with ant" as the type)

4. In the Projects panel, expand "Libraries" --> "JDK 15 (Default)" --> java.base

5. Use the trackpad to scroll through the tree view of packages

There is a noticeable lag in scrolling and it keeps going after you take your fingers off the trackpad