On a large dynamic XFA form, every script of an event copied the whole form
twice before it ran (the engine's live form to the script engine's tree, then
that tree to the flattened form the host works on), and every resetData call
rewrote and rescanned the whole document. On a 1,300-script form opening spent
its 3 s budget on these copies and on twenty resets, and skipped the last 850
initialize and calculate scripts.
The engine now sends the scripts of an event one shared tree (Arc) until the
live form changes in any way, and the script thread keeps the flattened form
it built from that tree; each script starts from a copy whose text is shared
(Arc<str>), so it costs a fraction of a flatten. Each script still gets its
own copy: nothing one script changes reaches the next except through the
engine. Resets in a row in one script's effects are applied as one reset of
the names together.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01CBVyQEwtmEw3mS1MoAiwrK
mtlcl410andClaude Opus 5.5
d65c465b1b