New Performance Scanning Tools on modern.IE Enable Faster Real-World Sites and Improved User Experiences

Today we released improvements to the modern.IE code scanner that help developers identify common patterns that improve real-site performance and can make a real impact on what users do on sites they visit. We also published a new tutorial that shows how used a combination of modern.IE and F12 tools in Internet Explorer 11 to improve their home page performance by 40% across modern browsers, including Internet Explorer. We continue to update modern.IE with tools that help developers spend less time testing browser compatibility.

New performance testing tools in modern.IE improve page responsiveness across modern browsers

New performance testing tools in modern.IE improve page responsiveness across modern browsers

Scanning for Web Performance

The scanner detects five common performance patterns. In many cases, the suggested fix is simple to make but produces a noticeable improvement in performance. Here is a summary of the new tools:

Image Optimization
This test scans the images on your Web page and suggests how page load speed might improve by using an image optimization service such as Over 60% of today’s Web site traffic is made up of images. Users visit Web pages on a wide range of devices – from mobile phones to large-screen TVs. Knowing when to send high- or low- resolution images to the browser can make a significant improvement on the user experience.

Compressed Content
This test identifies whether the Web page is using compression techniques like gzip. Similar to Image Optimization, site performance can improve by using content compression and then extracting and decompressing the content as the user needs it.

Prerendering Content
This test detects HTML markup that helps the browser identify which content a user is most likely to view next, so the browser can fetch that content in advance. This can significantly improve real-site performance because pages display faster as users navigate deeper into a site. A developer can request prerendering of an entire Web page, prefetching individual resource files, or pre-resolving DNS names. In all cases, it only requires one line of metadata to improve performance.

Flip Ahead Browsing
This test detects whether a Web page has implemented “prev” and “next” link relations which allow browsers to predict Web pages in a series (like when a user is browsing through a multi-page news article or a set of product search results on a commerce site. With flip ahead targets, the browser begins loading the page even before the user completes the swipe gesture. With more users than ever browsing with a touch-enabled device, the result is a Web page that feels more responsive and fast.

HTML5 Inputs
This test detects HTML5 Input Types – a standard, high-performance way to validate what a user in inputting. Prior to HTML5 Inputs becoming a Web standard, developers had to build custom validation functions in JavaScript which can be slower than built-in browser input validation.

Powerful Performance Tools in IE11 and on the Web

The modern.IE scanning tool detects many common ways that a developer might improve Web page performance and complement the IE11’s new F12 developer tools – including the UI Responsiveness and Memory profiling tools that help developers diagnose and fix performance issues. Developers often use a combination of performance tools – including and PageSpeed Insights – because each tool assesses different aspects of performance: server response, network connectivity, mobile browsing, etc.

The UI Responsiveness and Memory profiling capabilities in IE11’s F12 developer tools complement modern.IE for diagnosing and fixing Web site performance

The UI Responsiveness and Memory profiling capabilities in IE11’s F12 developer tools complement modern.IE for diagnosing and fixing Web site performance

Get Rewards for Trying the Tools out for Yourself

We are challenging developers to use modern.IE and IE11’s F12 tools to help build a faster Web through the 11% for 11 challenge (hint: there’s free pizza involved). You can learn about it on the Exploring IE Blog here.

As always, we look forward to hearing your feedback on ways we can improve modern.IE and F12 tools -- and help developers spend less time testing and more time building innovative Web experiences. You can reach out to us by e-mail or Twitter (@IEDevChat), and you can file bugs via Connect.

Sandeep Singhal
Group Program Manager, Internet Explorer

Comments (26)

  1. Yannick says:

    Awesome! Thanks for those tools, I love

    For Internet Explorer 12, I hope you guys are going to take a serious look at the options dialogue, it realy can use a make-over! It's like that since IE6. Come on guys, do something about it!

  2. Kyle says:

    Dear Microsoft IE Developer Tools Team:

    (replace [tag] with angle brackets as I had to use them to stop the blog from eating the tags)

    Just a reminder that:

    1.) [/img] is not a valid HTML tag so please don't waste time showing developers such garbage in the F12 developer tools.

    2.) style attributes ARE NOT MEANT TO BE UPPER CASE ESPECIALLY IF THEY WERE SPECIFIED LIKE EVERY DEVELOPER DOES IN LOWER CASE!!! e.g. it should be padding, margin, margin-top, display, position, etc. This is **incredibly annoying** and makes developing in IE a major pain!

    3.) Your developer tools are very, very slow – have you taken 30min to analyze why it is so slow and refactor some of that code? The Chrome, Opera, and Firebug tools load 2-5 times faster than yours! which is pretty slow considering you have full access to cheat and use the GPU.

    4.) I don't care how many tabs, on how many domains I open – sync the F12 tools with the currently focused (last-focused) window.  It is mind bogglingly painful to work with the IE dev tools when they are displaying for a window that you are not working with!  Copy Firebug – Please!!!!

    5.) Why do my hyperlinks have a shape attribute? DO NOT SHOW ME HTML DOM that I did not specify!

    6.) WTF is a cellPadding, cellSpacing, vAlign, bgColor, colSpan, rowSpan attribute doing in my clean HTML markup?!?!? turn that nonsense off ASAP!

    7.) Ditto for all the CSS rules in the right hand column that are in upper case! get with the year 2000 please Microsoft – Not a single developer uses upper case tags any more – none! – nada! – zip! – zilch!

  3. james says:

    The IE UI needs a makeover. UI looks like IE 7

  4. james says:

    Why is the back button in IE bigger than the forward button again? It looks so awkward and out of alignment.

  5. Martin Beeby says:

    @James, The back button is larger than the forward button since, according to telemetry, the back button is pressed far more often than the forward button – Martin Beeby, Developer Evangelist Microsoft UK.

  6. Christian Kirsch says:

    The locally installed tool (as available on Github) opens a HUGE security hole: If one uses it to check a local document that is password protected, the username and password are sent to Microsoft's server with the test results. This is unnecessary for displaying the results, and it exposes the user credentials.

  7. Nacimota says:


    1.) They do this for other void elements as well (link, etc.); I agree that it's ugly.

    2.) I don't know what you're referring to here. I can't see any style attributes rendered in upper case in the DOM tree or the styles list in the sidebar.

    3.) This isn't really conclusive, but in my own limited experience, the dev tools in Chrome and IE load at roughly the same speed.

    5. 6. and 7.) I'm not experiencing any of these things either.

  8. Esben says:


    The Dev tools in IE11 are much faster than in IE10. On my machine it opens nearly instantly.

  9. Steve says:

    Is there a fix for the Windows 7 IE11 uninstaller yet?… or a "Repair IE11" option since the garbage installed on my PC is now unusable (and won't uninstall)

    PS for anyone about to say how to uninstall IE11 please don't. We've been through the same steps over and over and it simply is not possible.

    @Microsoft – please address this! we need a standalone install/uninstall package.

  10. @Steve says:

    No it certainly is possible, you just have a somewhat rare situation where it isn't.

  11. hAl says:

    The scanner says this blog page is using al old version of jQuery and is using compatibility m odes making it up to 30% slower

    Also this blog using browser detection and non-optimized images and not using html5 inputs.

    Of course the blog page is also poor for use on mobiles devices.…/new-performance-scanning-tools-on-modern-ie-enable-faster-real-world-sites-and-improved-user-experiences.aspx

  12. Brian LePore says:

    Reported this in an email and to @IE on twitter, but the IE11 tiles + Notification section has a broken link to — it's missing the "http://".

    Oh no! Kraken says our images are not optimized! We can save 775 bytes with their service! Time for a major site re-design. :p

  13. pmbAustin says:

    So now that I'm all upgraded to IE11 on Windows 8.1 everywhere, I'm having tons of issues.

    On ALL IE11 boxes (tablets, laptops, desktops), I'm having serious issues with and … none of the browsers will log me in and remember me.  I use a "burner" account.  I can use it to log in, the login says "successful", but any attempt to do anything prompts me to log in again.  It doesn't REMEMEBER that I've logged in successfully.  I've gone through and made sure to set custom cookie handling (I had to do this in IE10 to get this to work) to "always accept session cookies" (why isn't this the default?!?)… no dice.  I've turned off "enhanced security mode", no dice.

    On two of the boxes, I have the sites in my "favorites bar", but the 16×16 favicon is blank.  I can't figure out how to get it to refresh, reload, or "get" the favicon.  Honestly, I've had TONS of favicon issues like this with IE (all versions), but it seems more pronounced since the upgrade (these favicons used to display the generic 'earth', now they're just blank).

    And on one of them, the "new tabs" page is just blank.  A bunch of blank squares.  Doesn't matter how many sites I visit, they're all blank, and remain so.

    It's like something got "clogged up" in some session state or registry setting or key somewhere, and nothing I've tried has managed to dislodge the blockage or fix the numerous issues.

    Any help here for any of this?  It's very frustrating to only be able to access the ability to get notifications and post comments on gizmodo and io9 from a Win7 box… which I normally don't use for anything.

  14. Greg says:

    @pmbAustin this sounds suspiciously like "DO NOT TRACK" is turned on and not enabling required cookies/sessions to persist.  Since Microsoft didn't consider the end user when they forced this setting on – perhaps their implementation is buggy (No Never! Not a buggy IE implementation!) – sigh.

    Try turning off the DoNotTrack feature, restart your browser and run through your scenarios again.

    If this is the root cause, please file a Bug Report right here on the IE Blog – Do Not file it in connect where no one will see it, verify it, reproduce it, and put a personal vote behind it.  Filing it on the IE blog (even with the broken comment form) is the best way to get attention for bugs found in IE (unless they are high security issues of course which should be filed properly)

  15. James says:

    @Greg, besides that broken site scenario, DNT is a good thing for your privacy and to secure you from trackers, privacy violators.

  16. Greg Hunter says:

    In Ecmascript test (, IE11 fails the following 7 out of 11578 tests:,







    Last six of them are related to date-time. The first one is Unicode mismatch.

    @IE team, please fix these in next update.

  17. pmbAustin says:

    Thanks @Greg… I turned off "DO NOT TRACK" (took me a while to find the setting), but that didn't change anything.

    I want to emphasize, this worked fine in Windows 8 with IE10.  But there isn't ANY machine I have where Windows 8.1 and IE11 work correctly.  This should be something people can easily reproduce, because I've reproduced it on desktops, laptops, and tablets…

    I cannot log in to my burner account on or (they share the same login).  It seems to work (it authenticates me and says successful) and then immediately forgets, and I get prompted to log in again if I try anything.

    I'd be shocked if it was just me.  It seems very clear that it's IE11 or the Win8.1 upgrade that broke something.

  18. Prior Semblance says:

    It's not necessarily anything wrong with IE11, it could be a problem with burner.  A lot of websites are pretty slow and lazy when it comes to supporting new version of IE.  I still run into websites that just detect IE and spit out code designed for IE6 whether or not it actually works in current versions of IE.  Not saying that's whats happening here, but just because a problem shows up in IE11 doesn't mean it is IE11s fault.

    As for Do Not Track, I don't think Greg actually knows what that is.  It would not cause the problems you are having unless the people programming burner were beyond incompetent (and even then, it would be 100% their fault)

  19. CvP says:

    Can anyone tell me what was IE team thinking when they removed the "CSS" tab?!!!

  20. CvP says:

    And why does stylesheets open in "debugger" tab? And why can't I edit them on the fly from there?

    Please see firebug for how it should work.

    I welcome all the great changes in F12 dev tools in IE11. It has brought much improvement for scripting and performance focused (ui responsiveness etc) dev works. However, it is literally worst if you are *designing* a page.

  21. pmbAustin says:

    Well, the good news is that I resolved my problem with  and … the bad news is that the nature of the solution makes me unsure whether it's an IE11 problem, or just a change in the site that coincided with my change to IE11.

    If I turned on "accept 3rd party cookies", then suddenly things work.  This was NEVER required before under IE10, but obviously this could be due to a change at the site… it just strikes me as hugely coincidental to the point I wonder if there was any change in the way IE11 handles cookies and implements these settings.

    I also find it bothersome/troublesome that most sites just plain won't work unless you go in and fiddle with cookie settings, over-riding the defaults to always enable session cookies, and NOW, apparently, having to accept 3rd party cookies just to be able to log in to fairly popular sites.

    Just a reminder, this all worked flawlessly with IE10 (with the caveat that I did have to over-ride default cookie handling and check the "always accept session cookies" checkbox).  And it continued to work without interruption on the two Win7/IE10 machines I've accessed the site with… it was just Win8.1/IE11 that suddenly had the problem.

    I tested a bunch of things, one setting at a time, to figure out what the issue was.  And the only thing that affected this, was the 3rd party cookies issue.  And that setting is NOT the same on Win7/IE10, and that works fine, so… I'm still thinking it's something weird that changed with IE11.

  22. Matt says:

    @pmbAustin does the 3rd party cookies get turned off as a sub component of the do not track setting?  I wonder if the two are somehow related and if so if Microsoft is aware that these default settings cause issues?  I've always wondered how this do not track setting affects common login scenarios like OpenID? does this still work?

  23. pmbAustin says:

    Toggling the Do Not Track setting has no effect.  Nothing had any effect other than enabling 3rd party cookies, which I didn't want to do, and don't have to do in IE10.

  24. Dimitris Dafalias says:

    Make a rich add-ons gallery,the way Firefox or Chrome have,at last!!I'd like to use my native browser for a change!

  25. Bill says:

    Has the Windows 7 / IE11 announcement been made yet?

  26. The Deeds says:

    IELTS is a very famous English test exam. At least thousands of people browse this website everyday

    IE11 on Windows 8.1 fails to load this website.

    The console is logging the following error:

    HTML1300: Navigation occurred.


    XML5660: The specified prefix has not been declared.

    File:, Line: 16, Column: 16

    Please fix it sooner than later.


    PS: here is the bug report…/ielts-website-is-not-loading-in-ie11

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