performance - IE9 on Window 7 slow (excessive rendering) -

performance - IE9 on Window 7 slow (excessive rendering) -

this bizarre frustrating issue please bear me total explanation.

preemptive note: not question of how improve dom/css performance. see when read frustrations.

we have re-worked out website cross-browser (e.g. < !doctype html >)

after pain html , css re-factoring, thought things fine. our website has pretty heavy dom incredibly sluggish point of beingness unusable. example: clicking select row takes 10 seconds until highlighted , check-box checked.

frustrations:

1) sluggishness not universal. ie9 suffers this. ie8, ie10, firefox, chrome speedy!

2) ie9 if changed in debugger ie8 documents mode becomes speedy! not in own ie9 mode.

3) while noticing sluggishness, super sluggishness (to point of unusable) on specific machines.

4) of course, 1 of machines client.

the question:

what perchance unique specific machines cause super sluggishness? cause these machines suffer more others?

things we've checked:

1) windows 7 updated.

2) not have windows update kb2976627 installed

3) not have windows update kb2670838 installed

4) disabled add-ons

5) stress 1 time again disabled shockwave flash object.

6) tried disabling "software rendering" in net options gpu used.

7) reduced windows display quality settings run maximum performance.

additional edvidence:

when display area gets smaller, responsiveness increases. happens when browser window made smaller or when dragged partly outside screen boundaries. when performance improves dom elements removed/hidden.

dynatrace shows huge amount of time spent on rendering.

webpage content:

there only: html, css2, javascript, jquery, simple images.

jqgrid 4.5.2

jquery 1.4.2

jquery-ui 1.8.2

there none of following: flash, video, css3, loaded third-party web content.

machines tried:

os: windows 7 enterprise n 64bit ram: 2 gb cpu: 2.53 ghz (2 processors)

os: windows 7 enterprise 64bit ram: 8 gb cpu: 2.67 ghz (2 processors)

ie9 version:

9.0.8112.16421 64-bit ie9 update version: 9.0.31 (kb2977629)

we tried uninstalling update kb2977629 no improvement.

repeat of question:

what perchance unique specific machines cause super sluggishness? cause these machines suffer more others?

i discovered explanation. feared when phrased original question jqgrid distraction (red herring). real cause answered in stack overflow article.

in short, our page contains lot of rounded corners (i.e. border-radius) styling. , there bug in ie9 causes rendering engine choke on this. 1 time styling removed, speedy again!

this explains why ie8 browsers , using ie9 ie8 documents mode fast. ie8 not back upwards border-radius didn't fall issue.

performance windows-7 jqgrid internet-explorer-9