I got my Retina iMac a few days early and I have been spending some time putting it through it's paces. Honestly, I feel like the police are going to show up at any minute and take this thing away...because it feels like it must have been stolen from a secret lab somewhere. It's just delightful to use.
While the primary use case I had in mind when purchasing this was photo editing, I'll probably spend just as much time with Xcode open as I will with Aperture open. Fortunately, testing Xcode performance is pretty easy: hit build, and use a stopwatch.
For my basic test I selected a fairly large project with about 1900 source files and a dozen or so external dependencies linked through CocoaPods. Then I made sure Xcode was finished indexing, cleaned, and built. My goal was to time the build and also monitor whether or not the fans spun up.
I ran the test on a Retina MacBook Pro (2012), a Quad Core Mac Pro (2010), and the new Retina iMac with the Core i7 processor upgrade. Here's the results:
- Retina MacBook Pro: 1 minute and 3 seconds
- Mac Pro: 1 minute and 7 seconds
- Retina iMac: 44 seconds
The iMac is definitely wicked fast. But running a parallelized build process for even that long does have some impact on temperature and therefore fan volume.
On the Retina MacBook Pro the fan did spin up for a second or two towards the end, but as soon as the build finished it spun back down. The Mac Pro never made a peep, of course. The Retina iMac's fans did spin up, and were definitely noticeable to me. Out of the 44 seconds, I would guess that the fan was active for around 10 seconds. As soon as the build finished, it spun back down.
I spent some time watching the fan speed with iStat Menus. The idle RPMs for the fan seem to be around 1200. At 1200 I basically have to put my ear behind the vent to hear anything. So I ran the build a few more times while watching the numbers and listening to what happens.
Around half way through the build the RPM would start to climb slowly. 1250, 1300. What interested me was that by the time it reached 1400 I could definitely hear it over ambient room noise. 1600 was pretty noticeable. Xcode never caused it to climb above that.
I'm definitely not excited about the fan but I'm not hitting the panic button about it just yet either. During normal activity, including incremental (non cleaned) Xcode builds, I haven't noticed any issues at all.