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  1. Qt
  2. QTBUG-89599

Performance regression in QTextDocument in 5.15

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Details

    • a62fa9b7cc520f3548356182bf5d6642c05be204 (qt/qtbase/dev) 4460711a802b4dfb6a9e71666185b15c59fb2e3a (qt/qtbase/6.0) 37f899ef7743cce5d5ba468debdce6f1156d9e96 (qt/tqtc-qtbase/tqtc/lts-5.15)

    Description

      We're a drastic worsening in performance of QTextDocument in 5.15 compared to 5.14. The offending commit has been bisected and identified as 09ee4282e5eedf5b44245e8b28b223339f87ddfa. With regards to paragraph count, the attached example has quadratic behaviour in 5.15, where 5.14 looks more to be linear in behaviour.

      Also attached a visualization of the difference where X is number of paragraphs and Y is the time it akes to perform the layout.

      Attachments

        1. main.cpp
          2 kB
          Gunnar Sletta
        2. Screenshot 2020-12-18 at 12.12.09.png
          110 kB
          Gunnar Sletta
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            frederik Frederik Gladhorn
            sletta Gunnar Sletta
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            Dates

              Created:
              Updated:
              Resolved: