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Every end tag rescans the pending end tag handlers of all still-open elements, so documents with many open elements take quadratic time. With an end tag handler on every element, "<div><b></b>".repeat(100_000) (1.2 MB) takes 1.34s; with this change, 0.05s. Real pages hit this through unclosed <tr>, <td> or <dd>. On a corpus of slow real-world pages the scan is 46% of extraction CPU; removing it halves the total and makes the worst pages 66-86% faster. Typical pages are unchanged. Find the handlers to run from the back instead, using the existing active count, so open elements are never visited. Reset the count before handlers run, so it stays correct if one fails or panics. Dispatch order and output are unchanged (identical on 104k pages).
remusao
requested review from
a team,
Noah-Kennedy,
jasnell and
orium
as code owners
October 8, 2026 10:16
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Every end tag rescans the pending end tag handlers of all still-open elements, so documents with many open elements take quadratic time. With an end tag handler on every element,
"<div><b></b>".repeat(100_000)(1.2 MB) takes 1.34s; with this change, 0.05s.Real pages hit this through unclosed
<tr>,<td>or<dd>. On a corpus of slow real-world pages the scan is 46% of extraction CPU; removing it halves the total and makes the worst pages 66-86% faster. Typical pages are unchanged.Find the handlers to run from the back instead, using the existing active count, so open elements are never visited. Reset the count before handlers run, so it stays correct if one fails or panics. Dispatch order and output are unchanged (identical on 104k pages).