I upgraded from a very solid X1e and have had great performance with X3.

Anderton
However, I agree with the comments about X3 being "snappier" and "smoother." I believe what happened is someone at Cakewalk took SONAR apart, sprayed it with WD-40, then put it back together again.
Meanwhile I haven't yet had a crash or freeze. I would have expected at least some "new update" hiccups or something. Very encouraging.

Close, but I used DoxIT Gold spray. I've found that spray works like magic :-)

Anderton
I agree with the comments about X3 being "snappier" and "smoother."
I haven't yet had a crash or freeze.

All in all very stable in my experience.
I have had some crashes but in my experience nothing out of the ordinary.  X3 seems to handle them much better and recover's very nicely.

It's fairly stable for me, although still getting blue screens when working with wave files...the more I work it, the higher probability it's going to happen. If I close and then load another project, it's usually not long before a problem occurs. I've since uninstalled and then re-installed in safe mode and am currently testing. 
 
Other than that, it's good. My Alchemy plug-in however asks me to locate its data every time I run a scan, which I do once on start-up. I'm not sure whether I need to do a scan every time though.

Great news all round guys!

With my limited testing (mostly playback & rough mixing) - X3 appears to be the be the best release yet.
My desktop died and has yet to be replaced so I been having to use my laptop, a HP Pavilion Duo-core Win 7 64bit system w 4GB RAM using Quad-Capture USB interface.
 
 
With this system and when using any previous version of Sonar I had to start with a clean boot and often I'd only get to work around 15 minutes on my 'big' project before Sonar would lock up, or my system would blue screen or something else would stop me.
I fired up X3 last week with Outlook 2010 and a bunch of other crap running just to see if I could do it (with this kind of a load using X2 my big project would have choked almost immediately after hitting play) and it ran fine - every now & then the playback would glitch slightly but it didn't crash.  I'm impressed.
 
 

aixmusique
Hey guys, is X3 rock solid? Did they improve it in comparison with X2a?
Thanks a lot!

I have the same problem as I did in x2a as I do now in x3b.  If I have my HP 2711x LED display connected via HDMI as an extended monitor on my notebook and then try and change driver in sonar from MME to ASIO sonar crashes out. 
 
I ran windbg against the dump file for a finger print analysis, and see an access violation occurred (0xc0000005).  I tried to post the analysis in this forum but the forum editor crashes out...

0:000> !analyze -v
********************************************************************************                                                                            
*
*                        Exception Analysis                                   *
*                                                                             *
*******************************************************************************
 
*** ERROR: Symbol file could not be found.  Defaulted to export symbols for CJLibrary.dll -
 
FAULTING_IP:
SONARSTD+924fe4
00000001`40924fe4 4c8b0cc2        mov     r9,qword ptr [rdx+rax*8]
EXCEPTION_RECORD:  ffffffffffffffff -- (.exr 0xffffffffffffffff)
ExceptionAddress: 0000000140924fe4 (SONARSTD+0x0000000000924fe4)
   ExceptionCode: c0000005 (Access violation)
  ExceptionFlags: 00000000 NumberParameters: 2
   Parameter[0]: 0000000000000000
   Parameter[1]: fffffffffffffff8 Attempt to read from address fffffffffffffff8

 
I have no problem with any other app on this system when I have the display connected, only sonar - then again no other app I have installed on my system uses ASIO.
 
The root cause I would think is the Operating System seems to think the HP 2711x display monitor has some sort of Intel Audio Device built-in but it doesn't...  I would think though sonar should handle this exception a bit better.
 
Anyway I posted in one of the hp forums about this but have not had any reply.

Jimmy Boy, we doth meet again!
 
Windows will show your display adapter has having an audio device, disable it.
 
And yet again, please display your system in your sig 
 
 

Btw, back to the OP....
 
X3b has been bloomin' marvellous for me. Very stable. Loving the New Blue Plugs, Loving the Tape Emulator, loving the colours and LOVING Melodyne.

markyzno
Jimmy Boy, we doth meet again!
 
Windows will show your display adapter has having an audio device, disable it.
 
And yet again, please display your system in your sig 
 
 

It is disabled - I have it disabled - in the sound devices it is disabled :P
 
In any case I sent a report to cakewalk support using that crash dump tool popup - maybe they can pin-point the bits of code that's not handling properly..
 
sig shmig :-
Windows 8 x64 premium home edition
HP ENVY 17" j005xt w/ nVIDIA 2GB
16GB ram - 2x1TB 5200rpm drives
Internal Sound Card IDT HD Audio
Scarlette 2i4
System Information
------------------
Time of this report: 10/14/2013, 23:37:48
       Machine name: HPENVY
   Operating System: Windows 8 64-bit (6.2, Build 9200) (9200.win8_gdr.130531-1504)
           Language: English (Regional Setting: English)
System Manufacturer: Hewlett-Packard
       System Model: HP ENVY 17 Notebook PC
               BIOS: F.23
          Processor: Intel(R) Core(TM) i7-4700MQ CPU @ 2.40GHz (8 CPUs), ~2.4GHz
             Memory: 16384MB RAM
Available OS Memory: 16160MB RAM