Connecting to a server with ~560 channels froze the UI for over two
seconds: every model event queued its own full tree rebuild, and each
rebuild expanded row by row with Swing's variable-height layout cache,
which measures every row on each expansion.
Coalesce model-change bursts into one rebuild and switch the tree to the
large-model layout (it already has a fixed row height), which only
measures rows on screen.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>