Creating a large JTree takes very long on macOS (works fine on Linux and ok on Windows).

The test program TestLargeTree.java creates 500 top-level nodes and adds 5000 nodes in each level. The top-level nodes are closed at the start. Top-level and first-level works, but opening the nodes on the first-level (showing the third-level nodes) takes more than 2 minutes. This behavior is sometimes observable when opening the top-level nodes too.

I captured two flame-graphs with async-profiler of this: flames2.html and profile.html

It causes additionally an OutOfMemory exception using 4GB of RAM. Increasing the heap size with -Xmx helps, as long as one doesn't open more than one node on the second level.