Prakash, this is weird. I am using similar configurations on Win/Lin without any problem. Could you please:
1) Take a snapshot by Profile Me Now (you have to turn it on in toolbar (right click, memory)
2) Use Java VisualVM to take a tread dump? Should be on Mac if you have latest Java 6.
Also could you send me project directly for evaluation?
Tnx, --Petr

we definitely need more details...

There were reported some problems about NB x Mac already
-http://forums.macrumors.com/showthread.php?t=780952
-http://netbeans.org/bugzilla/show_bug.cgi?id=173156
-http://netbeans.org/bugzilla/show_bug.cgi?id=173926

May it be the same case? Could you check if it's JavaFX specific?

Created attachment 92989 [details]
Screenshot of profiler view

Created attachment 92990 [details]
Profiler snapshot

I do see the problem on my windows 7 machine. The entire IDE freezes for several minutes when I open a JavaFX project with large amount of classes. I can not attach the project as it is Sun Internal project (Java Store). I'll try to create some project with dummy files. Mean while I'm attaching the screen shots of the profile and the profile snapshot for you to take a look

Winston,
Can you, before opening project, close task list view? This sounds to be related to this, compiler is not very efficient to give all necessary information thus the rest of IDE is not doing the best job as well IMHO. We will look into into it more deeply after break. You can send to me within Sun or give me location and I can pull the project out.

Could you run your IDE with increased stack size - it might help crashing. Meanwhile I am working on optimization of the error annotator which seems to take most of the CPU time.

Attempted to fix in http://hg.netbeans.org/javafx/rev/6c5faa31679b

The algorithm is sped-up and it uses an iterative rather than a recursive approach (that will prevent running out of stack space). According to my measurements it yields cca. 80% time savings but I would like to ask the reporter to confirm.

I'll test it when the Jan 04 development build is available. Now I see only the development build 201001020201.

I don't see the JavaFX development build here. 

http://bits.netbeans.org/download/trunk/nightly/latest/

How do I get it for me to test it?

Please provide me the latest JavaFX IDE bits. Netbeans 6.8 with out this fix is killing my productivity.

I couldn't wait, so I build it from the source. The IDE response is much better and usable. 

Quick question, how do I build the Mac installer from NB source?

I tried 

ant build-mac -Dapp.name=nb6.8

but getting the error

BUILD FAILED
/Users/winstonp/nb-src/javafx/harness/suite.xml:205: Warning: Could not find file /Users/winstonp/nb-src/javafx/harness/launchers/app.exe to copy.

I tried 

ant build-mac -Dapp.name=nb6.8

but getting the error

BUILD FAILED
/Users/winstonp/nb-src/javafx/harness/suite.xml:205: Warning: Could not find file /Users/winstonp/nb-src/javafx/harness/launchers/app.exe to copy.

Unfortunately, at the moment we have some troubles building the NetBeans 6.8 patched version of the JavaFX plugin (based on JavaFX 1.2 SDK) - mostly thanks to update of JavaFX SDK to 1.2.2 ...
If you don't mind using the Soma based plugin you can find the latest builds at http://big-mac.czech.sun.com/hudson/job/NetBeans-JavaFX-Soma/

Unfortunately, I can not use Soma, because it is not binary backward compatible. Also, the sources are not compiling. Java Store is going to be released in another couple of weeks. So must be built using JavaFX 1.2.1.

Is there any chance you could provide me just the module with the patch? With out the patch it is very painful to use the IDE.

The fix has been ported to release68_fixes branch as
http://hg.netbeans.org/javafx/rev/852d9e25c7ef

(changeset shared with #178404 and #178838)

I tried to open a JavaFX project with 500 files and it works.

Verified in the NB 6.8 patch1  2010-01-25_21-27-59