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iMac performance evolves through the years

No one touted the iMac as a computing power house when it first began shipping 10 years ago today. But at some point in the ensuing decade, the iMac evolved into a viable pro system for many users, blurring the line between professional and consumer desktops.

Just how much has it evolved? In honour of the iMac's 10th anniversary, we decided to use Macworld Lab's collection of older iMacs to find out.

Macworld readers are always asking the Lab to compare current Mac models to vintage systems. The problem, of course, is that a G3-based iMac can't run all of the applications included in Speedmark 5, our test for benchmarking Macs. Still, we thought we'd mark the occasion by trying to quantify the progress in performance made by the iMac over this last decade.

What we tested

To that end, we assembled (and reassembled) five iMacs from the past, with systems from the G3, G4, G5 and Intel eras all represented. We upgraded the RAM as best we could and loaded the latest version of OS X that would run on each machine. We picked 12 different tests that could be run all of our systems, as well as our Photoshop suite, though even CS2 wouldn't run on our earliest G3 iMac.

We wanted to include the original 233MHz Bondi Blue iMac G3, but unfortunately, it didn't pull through its RAM upgrade surgery. (The original iMac is a bear to upgrade.) The closest we could get to the original model was a 333MHz Grape iMac G3. Originally, this fruity iMac shipped with just 32MB of RAM. We were able to install two 256MB DIMMs, but the iMac only recognized half of each stick, so instead of 512MB, we ended up testing the system with 256MB and OS X 10.3.9 Panther-the latest version of the OS we were able to install.

Next we picked the iMac DV SE, running a 400MHz G3 processor. We were able to get this system outfitted with 1GB of RAM, and OS X 10.4.11 Tiger. This was the first iMac to feature FireWire, making file transfers a whole lot faster. It's also the Mac that both my children and my in-laws use on a daily basis, so I have a personal interest in how it performs.

We also tested an iMac G4, with an adjustable 15-inch LCD display; we were able to run Tiger with 1GB of RAM on this system as well. Our final models included a 2.1GHz iMac G5 with built-in iSight camera and the current entry-level iMac, a 2.4GHz Intel Core 2 Duo model. Both of these final two machines were tested with the latest version of Leopard (OS X 10.5.4) and 1GB of RAM.

Testing notes

Before we start comparing the performance of all of the models, let me point out a couple of issues that arose during testing. First, in order to get applications that would run on all of the systems, we needed to use primarily older, pre-Intel applications that put the current shipping iMac at a disadvantage, since it had to run many apps like iMovie, iPhoto, Microsoft Office, and Photoshop using Apple's Rosetta translation technology; as you may remember from the Intel transition, running programs via Rosetta can dramatically slow down performance. For that reason, the G5 iMac was able to keep up with, and, in some cases, top the Intel iMac. Had we been able to run Intel-native versions, those results would have been very different.

Secondly, we gave the 333MHz Grape iMac a bit of a break as the hard drive was not large enough to hold all of the test files and applications. So, unlike with the other iMacs--which had all apps and documents installed for the duration of the testing--we were swapping applications and documents as necessary to fit onto the iMac's less-than-roomy 4GB hard drive.

The results

Overall, the results show marked improvement at each step down the iMac family tree, with big performance jumps between the G3, G4, and G5 processors. I think the above charts speak for themselves, but I'll call out a couple of the more interesting results. For instance, compressing a 512MB file took 7 minutes 28 seconds on the Grape iMac, 5 minutes 45 seconds on the iMac DV, 3 minutes 15 seconds on the G4 iMac, 1 minute 3 seconds on the G5, and just 44 seconds on the Intel iMac: you could run that same test 10 times on the Intel in the time it took the Grape to finish the task just once.

The biggest difference between the G3s and the Intel iMac was the Camino test. Downloading Web pages over a closed network took a whopping 40 minutes on the Grape iMac, 20 minutes on the G3 iMac DV, nearly 12 minutes on the G4 iMac, about 2 minutes on the G5 iMac, and 55 seconds on the Intel 2.4GHz iMac.

As mentioned above, the Intel iMac is running many of the applications under Rosetta, so results from Word 2004, Photoshop CS2 and the older iLife applications don't compare very favourably to the results of the G5 iMac. In our Universal Binary application tests, we found the Intel Core 2 Duo iMac to be 45 percent faster than the G5 iMac in Photoshop CS3 tests and 42 percent faster in our iTunes MP3 encode tests.

And while those results are dramatic, I think the fact that the original iMac can't even run 11 of the 17 tests making up the current version of Speedmark is just as striking.

It's one thing to say that performance has progressed over the past decade; it's quite another to see the extent of that progress. And maybe it will finally convince my father-in-law that it's time to upgrade.

[James Galbraith is Macworld Lab director.]