I have a similar problem, not caused by data on my disks -- I believe that Waves is the culprit, either going to the internet for licensing fun, or if the internet is disabled, causing a wait for an access timeout.     
 
 

Well, only 4 minutes wouldn't explain it. If you do Select All (ctrl+a), does the selection only include the same 4 minutes? What I'm curious about is whether maybe there is data way out there in the timeline that you might not be aware of.
 
Also, does ctrl+s (save) take a long time too? or only initial load? Is the project file itself less than a couple of MB?
 
If you freeze the synth tracks, does it load faster?

gswitz...
 
thanks, I will check your suggestions!
 
freq

I keep my projects on a separate drive so mine will always take longer to load.

Most of the time when projects take long to load it is due to plugin load times. Some plugins take an enormous amount of time to load. I've also seen some plugins like Ozone and Melodyne throw a lot of exceptions which slows down the load process a lot as well. You could try and narrow it down by saving a version of your project with plugins removed and see if that change anything.
Another thing that can slow down load is lots of audio snap regions.

Would it be possible, each time Sonar loads, to measure the startup impact of Sonar itself, individual plugins, audio snap etc and present the results in a dialog accessed from the Utilities menu? This might help with the various inquiries about startup time, and also might encourage recalcitrant plugins to lift their game :) Windows 10 does something similar in the Start-up tab of the task manager.
 
Cheers, Peter.

Twenty seconds? That's it?

Noel Borthwick [Cakewalk]
Most of the time when projects take long to load it is due to plugin load times. Some plugins take an enormous amount of time to load. I've also seen some plugins like Ozone and Melodyne throw a lot of exceptions which slows down the load process a lot as well. You could try and narrow it down by saving a version of your project with plugins removed and see if that change anything.
Another thing that can slow down load is lots of audio snap regions.

Thanks Noel.. will try it.
 
Freq

I find that most of my projects have about 5 or 6 plugins, usually DP, Rapture, ZEta +2, AD2, etc., and it takes about one minute to open.  I found that if I freeze all the MIDI tracks, then it takes about 25 to 35 seconds to open.  I'll gladly accept a larger file to get it to open faster.  BTW, I'm not using an SSD, just a regular hard drive.