[Solved] Maintaining project tempo when importing clips from browser

There are a lot of variables, but here are the main ones.
 
Groove clips (Apple Loops and REX files, too) speed up better than the slow down. If there's a clip at 120 BPM, it will probably sound fine at 140. It will probably sound horrible at 100.
 
Creating really good "acidization" (the technology behind groove clips) is not trivial and is time-consuming. For example Sony's acidized sample libraries are done very well, and stretch as well as can be expected over a wide range. Others just invoke Sonar's Ctrl+L or Acid's prelminary attempts and leave it at that, which does not end well.
 
You can Ctrl+drag when slip-editing to use DSP to change duration. The drawback is that if you change your mind about the tempo, you'll have to do this again. If the tempo changes, this will not follow along whereas Acidized files will. You also have to bounce the slip-edited clip to itself to use the high-quality offline rendering algorithm instead of the real-time preview mode.
 
REX files are best for clips with short, percussive, highly defined hits but terrible with pads. Acidization can work very well with pads (I've developed n unusual technique that creates pads that work from 10-500BPM, which is definitely not the norm) but sometimes delivers as good results with percussion as REX and sometimes not. In all cases, pitch transposition is a crap shoot. You're much better off using Sonar's Transpose function.
 
In a previous lifetime, companies would pay me to acidize their files because it's such a PITA but I'd done so many I knew what I was doing, and could make things happen fairly fast.
 
You may find these helpful:
 
http://www.harmonycentral.com/articles/how-to-acidize-wav-files-in-ca-30956572
http://www.keyboardmag.com/compose---arrange/1329/tips-and-tricks-for-loops-and-beats/29601
http://www.soundonsound.com/sos/mar02/articles/sonarnotes0302.asp
http://www.soundonsound.com/sos/sep05/articles/sonartech.htm
http://www.soundonsound.com/sos/sep11/articles/sonar-tech-0911.htm
 
 
 
 

There's something about your question I don't understand. You say that preview is set to the project tempo; if you drag the clip into the track (ctrl-drag isn't necessary),you say "it takes time to find the exact tempo it was playing at in preview." However, it should play at the same tempo as what you heard in the previewbecause the browser gets its tempo from the project. 
 
If you're asking how you can change the project tempo to the clip's original, non-looped tempo, first look at the clip name, which often incorporates the tempo; then set the project tempo accordingly. If no tempo is indicated, bring the clip into the project, then double-click on it to open the loop construction window. The LC window's BPM field will show the clip's original tempo (and often more precisely than a tempo incorporated in the clip name).
 
If these options don't address what you want, please provide more detail on exactly what it is you want to accomplish.