Twenty Fourteen: Scroll lag in Windows

[karmatosed]

There is a scroll lag when using Windows 7 and 8.1. with IE 11.

This has been confirmed in 3 cases now. Whilst, I am not sure if the culprit, it is worth noting that In one of those cases the console log showed the following:

body.scrollLeft is deprecated in strict mode. Please use 'documentElement.scrollLeft' if in strict mode and 'body.scrollLeft' only if in quirks mode. 
​http://s1.wp.com/wp-content/blog-plugins/wordads/twentyfourteen-v2.css?ver=2013-02-15 404 (Not Found)

[lancewillett]

Thank you for the report. Any chance of a screencast to see it in action?

[karmatosed]

Certainly, there is one here: ​https://i.cloudup.com/EGXr0kDFHb.mov. This was with browserstack with increases the lag. I've also got someone to test this and they got it on a local machine - this ruled out just being browserstack lag.

[celloexpressions]

I can confirm this - remember seeing it a bit during development but didn't realize the theme was at fault (not nearly as bad as in the screencast, but still an issue in IE11 desktop on Win 8.1). I have a feeling that this is closely related to the JS that does the sticky header when there's a header image - which doesn't work in IE (#25144, which is only partially "fixed"). It seems to disappear when there is a header image, but the lag is so slight in the first place that I can't be sure.

For me, the lag is just slightly unresponsive scrolling; the re-rendering part is probably the browserstack layer but might show up on slower machines too. I think we need to test a slow machine to confirm that this is a big enough issue to look into.

[lancewillett]

Agreed needs more testing, especially if anyone has access to a slow machine running Windows natively — not a VM on a fast Mac. :)

[karmatosed]

In some housekeeping, I retested this today and I can't replicate it. As a result, I'm going to close this up now and keep an eye out incase someone else reports this. I have changed machine and connection since reporting and whilst that shouldn't be the case, perhaps it is.