Painfully slow MXML editing in Flash Builder 4.0 and 4.5

We have been seeing an issue where in some of our MXML code, the editing gets painfully slow. As I type, it can take many seconds for the characters to appear on screen. It makes some of our components basically un-editable within Flash Builder.
I’m trying to get a good repro together for Adobe, and today I narrowed down the issue in one of our components to the presence of a mx:DataGrid tag with multiple attributes.

Take a look at this video I made illustrating the issue.

Has anyone else experienced this?

UPDATE (05/31/2011): I can get around it by subclassing DataGrid as something like DataGrid2. I don’t actually do anything different in my subclass. I just use that in my component instead of referencing DataGrid, and it works like a champ again.

P.S. We had already disabled Design mode a long time ago, so unfortunately, that is not the culprit in this particular case. I’ve also attempted to disable everything “content-assist” related within the MXML Content-assist settings, and that didn’t seem to help. I look forward to discovering a simple setting that can bring the performance back!

5 Responses to “Painfully slow MXML editing in Flash Builder 4.0 and 4.5”

  1. Javier Julio May 30, 2011 at 1:09 pm #

    Yes I have but not for a specific component. Turn off design mode. At work several of us started to notice slow down in Flash Builder and that made a huge difference. No waiting now at all when opening or switching to a file. The option is hidden since it’s not in Preferences. If I remember right it’s in the Window menu.

    • Taytay May 31, 2011 at 1:50 am #

      Thanks Javier! Unfortunately, we already turned off Design mode long ago, and that is not the cause of the issue in this case. :(

      I did find a way around it though by inheriting from DataGrid, and will update the post to reflect my new findings.

  2. danel kirch May 30, 2011 at 1:17 pm #

    Yea, i’ve experienced same within my FB 4.5.
    until now i really didnt know what was causing it, but thanx for discovering it and bringing it to daylight!

  3. Constantin June 8, 2011 at 11:30 pm #

    That slowdown most probably is caused by component properties window. If you set properties window to list view not graphical view It might solve the problem.

  4. Rich Sadowsky June 30, 2011 at 7:25 am #

    I have seen this too and complained about it many times. I just had a case where it took almost 10 minutes to switch from source to design mode. I was about to Force Quit which would have been really bad since there was unsaved source. I don’t know what triggers it. Sometimes it switches in seconds, even after the page begins to get loaded up with more Flex components. But other times I have to go take a break and come back. This is a pretty serious bug imo. I have a MacBook Pro with i7 2.66 Ghz and 8 GB of RAM so I have trouble believing my machine is just too slow!

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