Hi.  This is probably a strange problem, but it happens every time I use Sonar. I record a lot of tracks and sometimes some long takes (raw recordings of sound effects etc) and sometimes I'll drag sound clips far to the right (past the 10 minute mark) just to get them out of the way for a while.
 
But when I bounce down to a stereo mix it takes a long time (15-20 minutes) and I end up with a really long song that is mostly silence. The mix I just did is now over 60 minutes long even though I just went though and cleaned out anything that was past the 13 minute mark. 
 
So, is there some way I can limit the bounce process? There doesn't seem to be a time setting on that page. I know I can highlight just the things I want to mix but that's not easy with my songs. I have a lot of tracks (142 in this one) and the songs are often 10 minutes long. 
 
Or, conversely, is there a way I can get it to stop thinking that it needs to keep going well past the last sound/midi clip in the project?
 
Thanks!
Scott

Try this... press Ctrl+A to select all tracks. Then choose Edit > Select > By Time and enter the start and end locations for the export. Now do the export as normal and it should only export the time frame you entered.
 
Scott

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Or after selecting the tracks, click-drag across the timeline. There are several ways to select a time range to export.

Ahhh Select by Time is perfect!  Well... it would be MORE perfect if Sonar didn't think my song was 1276 bars long, but at least this saves me a lot of time!
 
Thanks!!
Scott

I had the same issue, sometimes creating an envelope would put something way beyond anything I'd recorded.  I set the Now Time marker at the end of my song, and when exporting select Edit->Select->Thru=End.  Same effect as entering and end time though.  It works for me as I put an END marker at the end of my song, and it's a quick way to just drop the Now Time marker there.

There is also the issue that a lot of wave files (even small sample files)  have a timestamp that says that they should start at 1 hour into a project (some silly ProTools convention).  If things are loading at 1 hour in, you might want to disable 'import files at timestamp' in preferences.
 

If you hit Ctrl + End and your Now time marker relocates to somewhere other than the notional end of your project, then there most definitely is something out there that's causing it.
 
First check your event list - select ALL tracks and scroll to the bottom of the screen to find out where the last events are.
If there's nothing there, you need you check envelope nodes, tempo changes, meter/key changes. These last 2 have their own dedicated View screen so open it up and examine the contents of each.
 

Or review threads from like 10 years ago.

!!!No offense to the OP intended!

But in all seriousness just select everything you want included. Many different ways to go about doing this. Pain in the rear to explain. But experiment and you till see Sonar only exports selected material. If nothing is selected then it exports wherever it thinks the end is. Good luck.