My system is an I7 860 4 Go of ram. The processor is not loaded during the loading of the project. Sonar takes 10 %. The project has 10 Vsti nothing special. I have other project of the same size and the opening is quicker...

FWIW, 4GB of RAM is running a little lean... especially if you're using 10 simultaneous soft-synths.  As was mentioned, I'd add another 4GB.


Some soft-synths load samples into RAM... or load RAM buffers.
This can take some time...
A SSD speeds up this process.

When the project is open I still have 2 GO of ram free... So I don't think adding ram will be useful I have another project with 30 Vsti (created in sonar x1)that use 2.5GO/4GO of ram when open and sonar opens it in around 1 minute. The problem is this new project created by sonar X2 that takes 5 minutes to open... I have monitored the harddrive use during the opening and nothing special... The hardrive is not used à 100%.

When the project is open I still have 2 GO of ram free... So I don't think adding ram will be useful I have another project with 30 Vsti (created in sonar x1)that use 2.5GO/4GO of ram when open and sonar opens it in around 1 minute. The problem is this new project created by sonar X2 that takes 5 minutes to open... I have monitored the harddrive use during the opening and nothing special... The hardrive is not used à 100%.

4 gigs of ram is not enough even though you think it's fine. Try freezing all the VSTi's and save the project. See if it opens faster with the freeze in place. Remember, windows may be writing stuff to the disk if it thinks the memory is low and it needs to use some memory to function.

Have you done any midi editing?  If so bounce the midi tracks.  Also empty picture cache in sonar.   

The problem is not during the reading of the track that works perfectly but during the opening (the time between the moment I select my project and the moment that the project is launched in SONAR and I can edit it)

How big is the project file compared with some of your others? Do you have audiosnap enabled on any large clips? When you say CPU uses 12%, that may be a single core (thread) being used 100%, meaning it may have nothing to do with I/O or swapping. Some detective work might be to make a copy of the project and then whittle it down little by little until it suddenly opens quickly.

The size of the project is around 1 Mo. I do not have any snapshot. None of the thread is full loaded and the harddrive use is not at the maximum. I have checked this information with the ressources monitor of Windows 7.

Hum... I have uninstall sonar and re install it and it seems to work fine now... Thank you guys for your help !!

I had to ditch X2 and go back to X1. Got sick of the weird behavior on my Windows 7 x64 system. Its powerful enough to run anything. But X2 still likes to eat away at the CPU upon startup. It's sluggish compared to X1, which tells me that it feels bloated. For all I know it could be reacting to certain plugins. But this occured before installing any. I struggle and struggled. Eventually, I open X1, and lo and behold, no problems whatsoever on the same system. 

I just wish Cakewalk would get their software bugs minimized before throwing in more "luxury" features to crows up the software. You just end up with more problems and never a smooth running program. Hey 8.5! I'm starting to miss you!