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Support Article

Repeat Grid hover and select very slow in IE 8



User has a Grid Repeat Layout showing read only data with 11 columns. The mouse over (row highlight) and click (row select) events are extremely slow in Internet Explorer 8 but perform fine in Internet Explorer 10.

Performance in Internet Explorer 8 is fine when the grid shows less than 10 results but degrades as the number of results increase.

When there are 100 results (which is the page size) then a row takes several seconds to highlight on mouse over.

Error Messages

Not Applicable.

Steps to Reproduce

Create a repeating grid as mentioned in the Summary section.

Root Cause

The root cause of this problem is in a third-party product.
The platform support guide specifically mentions about client side performance issues when using Internet Explorer 8 and recommends using other browsers that don't have such performance issues.


Internet Explorer 8 continues to work with  Pega 7.1 with the caveat that Internet Explorer 8 is known to cause client-side performance issues when operating in Standards Mode. Some screens, especially grids and lists which display large amounts of data, may experience sub-optimal performance with Internet Explorer 8.

Pega strongly recommends using another browser which does not have these performance issues, such as
Internet Explorer 9, Internet Explorer 10, Internet Explorer 11, Chrome, Safari, or Firefox.

Microsoft is no longer updating
Internet Explorer 8, and instead points customers to Internet Explorer 10 or Internet Explorer 11.

Therefore, Pegasystems cannot address these client-side performance issues reported with
Internet Explorer 8. User should consider carefully before using Internet Explorer 8 as the target browser with  Pega 7.1.

The main culprit is
Internet Explorer 8 version's handling of HMTL tables in Standards Mode.

The UI Engineering team have continued their research today to understand the cause of the
Internet Explorer 8 performance behaviour.
The following link demonstrates that this scenario is not PRPC specific,
Internet Explorer 8 is known to have performance issues with tables, especially when nested inside other DIVs and tables:

Internet Explorer 8 attempts to re-calculate the offsets of the table cells causing performance degradation when the number of rows and columns increase.


Perform the following local-change steps:

1.  Configure the grid with the "Pixels Fixed" width option .
The issue is compounded in the case of grids with "Fill 100%" width option.  

 2.  Remove 'row hovering' and 'row focus'.

These are applied in two places and must be removed:
      a. Layout properties > Presentation tab > Enable row Hovering.
      b. Layout properties > Actions tab > Set focus action.

In both cases JavaScript is used to set CSS classes to each cell in a row. In testing row hover was increasing CPU load by 100% in
Internet Explorer 8.

While they visually can enhance the screenbut it is achieved by attaching a style to each cell on a row using JavaScript , so ten columns in ten places JS has to attach a class onHover and ten places to remove it onBlur. Likewise focus.


Published April 25, 2016 - Updated October 8, 2020

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