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  1. ZK
  2. ZK-4158

bad render performance when using themepack themes

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    Details

    • Type: Bug
    • Status: Closed
    • Priority: Major
    • Resolution: Fixed
    • Affects Version/s: 8.5.0, 8.6.0.1
    • Fix Version/s: 8.6.1
    • Component/s: Theme
    • Security Level: Jean
    • Environment:

      Description

      Steps to Reproduce

      run the attached example measure-onresponse.zul
      scroll down to trigger new rows to be rendered

      observe the browsers console

      Current Result

      chrome breeze:

      (index):881 zAu._onResponseReady: 0.283935546875ms
      (index):881 zAu._onResponseReady: 0.036865234375ms
      (index):881 zAu._onResponseReady: 0.02392578125ms
      (index):881 zAu._onResponseReady: 77.556884765625ms (that's the render time)
      

      chrome iceblue_c:

      (index):881 zAu._onResponseReady: 0.261962890625ms
      (index):881 zAu._onResponseReady: 0.02099609375ms
      (index):881 zAu._onResponseReady: 0.017822265625ms
      (index):881 zAu._onResponseReady: 574.68896484375ms
      

      when using "iceblue_c" chrome takes ~700% time to render the new rows

      Expected Result

      equal or marginally different render time

      Debug Info

      looking into the performance profiler, shows most of the time is spent during "Recalculate Styles" indicating a CSS problem

      Root Cause

      certain combinations wildcard CSS selectors negatively affect the CSS performance

      e.g.:
      just adding those 2 empty style rules to the breeze theme, causes a similar performance drain:

      .z-combobox-input[readonly]+* { }
      .z-combobox-disabled>*:hover+* { }
      

      replacing the wildcards with specifc selectors helps (not sure if a is the correct element, the implementor needs to check carefully)

      .z-combobox-input[readonly]+a { }
      .z-combobox-disabled>*:hover+a { }
      

      the attachment contains the iceblue_c zk.wcs with the problematic 9 rules commented out

      commenting in a single of them doesn't make it slow, only certain combinations of at least 2 of these rules cause the slowdown

      Workaround

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              Assignee:
              Leon03 Leon03
              Reporter:
              cor3000 cor3000
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                Dates

                Created:
                Updated:
                Resolved:

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