The load-time Byte Buddy agent cost ~420 ms on every launch before the
splash screen could show. FxThreadPlugin now weaves @FxThread at build time
(byte-buddy-maven-plugin, process-classes) with the same inlined advice and
method matcher as the agent, and marks each woven class @FxThreadWoven.
FxThreadAgent.install() only attaches when the application's classes run
from a directory (an IDE run), where an incremental compiler may have
overwritten woven classes, and then weaves only the classes without the
marker, so nothing is woven twice; -Dpholio.fxthread.agent=always|never
overrides the choice. A Maven-built jar starts with no agent: the splash's
first paint moves from ~0.83 s to ~0.47 s.
The measurements behind this are in .claude/plans/startup-time-analysis.md.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011xpLSeYKKHX6o16jzYLgZv
chris.giteaandClaude Opus 5.5
ded9907bcb