Export Audio taking AGES

[DanMason]

Hi, this happened to me for the first time tonight. 
Exporting a 5 minute track to FLAC format, 48k 16-bit. This would normally take about 30-60 seconds. At the moment it's on course to take about 40 minutes.
Now this is radically different from similar tracks I've worked on recently in that it uses quite a lot of plugins, and several of them are new to me. 
So my main question really is whether the use of particular VSTs within a project is likely to have a major effect on the time taken for mixing down audio. I'm less bothered about tracking down a culprit initially. 
It's hitting the CPU pretty hard during this (30%) although I notice Cakewalk is using very little RAM (400MB). 

 

[Xoo]

Assuming you have a multicore CPU, do check that the following setting in aud.ini is set to 1:

AllowOfflineRenderMixThreads=1

The help file has this the wrong way round, so if you've set it to 0 (intentionally or otherwise), you'll be using just one core for exports.

[DanMason]

Hmm I've answered my own question here. Unfortunately it's an embarrassing answer!

When I played back after the export had finished, it was the entire 150 minute project instead of the 5 minutes I'd selected.

My first time using the "Export" shortcut in the menu bar instead of going via the File menu... turns out I hadn't noticed that there are two radio buttons and the default is "Project" rather than "Selection".  D'oh!