IE9 RC Now Available

The Release Candidate of Internet Explorer 9 is now available. I’ll be posting my IE9 RC Minor Changes list sometime in the next week—we’ve made a ton of improvements since beta, and I’m excited to talk about all of them.

For now, I’ve just posted an article on the Fiddler blog explaining how IE9 RC introduces some cool improvements for proxy-based debuggers like Fiddler.

I hope you enjoy the RC as much as I do,

-Eric Lawrence

Comments (9)

  1. sorry to bother says:

    during preview 1-7 to beta my configure can gpu rendering, but install rc the option gray out only software rendering. fishtank test crawl… why? how to force gpu rendering?

    my configure:windows 2008 r2 , ati 4850 update to  latest 11.1 driver dx11  already installed , cant fix it.

  2. EricLaw says:

    @sorry: If you cannot configure GPU rendering, and it's disabled/greyed out, that means that your driver version is blocked, either due to crashing bugs or severe performance problems. After verifying your driver version (what version is it?) you'll need to contact ATI and ask when they will be updating the driver.

  3. ietest says:

    installed latest vertion 8.812.0.0. dosnt work (the older vertion dosnt too)

    i run every test in testdrive site with preview 1-7 and beta, performance is excelent. during months normal use find no major render problem.

    now RC disable gpu render.  maybe there is some false check.

  4. Tommy says:

    Just a thought, shouldn't 64bit performance be equalt to or better than 32bit ??? I'm getting better fps and such with the 32bit bin's

    System : 2xXeonE5405 2GHz(8 cores total), 8Gb RAM, Nvidia Gforce 250GTS 1GB RAM, Windows 7 64bit Enterprise

  5. EricLaw says:

    @Tommy: Nope. See…/q-a-64-bit-internet-explorer.aspx


    Notably, in IE9 there's one other major difference between the 32bit and 64bit versions of IE. IE9 includes a new script interpreter which is much faster than the script interpreter in IE8. However, 32bit IE also includes a Just In Time  (JIT) script compiler which converts script into machine code before running it. There is no JIT compiler for 64bit IE. So, for benchmarks like SunSpider (and script-heavy sites) 32bit IE9 runs script up to 4 times as fast as 64bit IE9 (which itself runs script around 5x as fast as IE8). So, you could end up paying a significant speed penalty when using 64bit IE9 vs using the default 32bit version..

  6. Bradley Grainger says:


    We found two issues (new to the RC) that break our application that hosts the WebBrowser2 control:…/javascript-function-return-value-is-not-passed-to-com-caller-through-idispatch-invoke…/ie9-javascript-error-when-accessing-dispid-value-propget-method-on-com-object

    We haven't seen any feedback from Microsoft on either of these issues, but we know that IE9 is scheduled to be released on Monday. Any chance you could let us know what the status of these bugs is?


  7. EricLaw [MSFT] says:

    @Bradley: I can confirm that the second bug is fixed in the current build. If you can send me (ericlaw at microsoft) a link to a program that repros #1, I'm happy to try it out.  Thanks for the good bugs!

  8. Bradley Grainger says:


    Thanks for the quick response!

    From this KB article about Netflix (…/2512239) I found that the FEATURE_USE_LEGACY_JSCRIPT registry key works around both the issues I mentioned (with IE9 RC and our application). Even so, it's good to hear that the second will be fixed in RTM.

    Regarding a repro for #1, another Connect user posted…/ie9-rc-javascript-will-not-return-values-when-sinking-managed-c-events, which sounds the same as the issue we were experiencing, except he was using managed code (instead of ATL components, like we do). It's not a complete packaged repro, but it appears that if the source code at…/313891 is modified so that ControlEvents.ClickEvent is typed as returning int, and ctrl::ClickEvent is changed to return an int, the managed code never receives the value.

    Unfortunately, I'm out of the office for the rest of this week, but I could try to get you a repro early next week. Thanks for your help!

  9. EricLaw [MSFT] says:

    @Bradley: I tried the C# example code by chasing down the chain of pages, but I couldn't even get the original code to work properly. .NET UserControls are blocked in the Internet Zone, but even trusting the site, adjusting CAS Policy, etc, didn't help. I'll look for your mail, thanks.