Apple Makes the Switch: iMac G5 vs. iMac Core Duo

iLife '06 Performance with iMovie HD

The next application that I looked at was iMovie HD, a part of the newly announced iLife '06.  There are two primary focuses for performance in iMovie HD: video import speed (if you are dealing with a non-DV or non-iSight video source) and effect rendering speed.  I focused on the latter, measuring the time that it takes to render various transitions and video effects in iMovie HD. 

Note that all of the transitions and "Video FX" are single-threaded, so there was no performance difference on the iMac between running with two cores or one enabled. 

First up are the transition rendering times. There are 15 transitions in iMovie HD that can be placed between two separate clips. I timed the amount of time that it took for the transition to be rendered upon inserting.  Each transition was timed three times and the results were averaged - the average time is reported in the table below:

iMovie HD Transition Rendering Performance in Seconds (Lower is Better)	iMac G5 1.9GHz	iMac Core Duo 1.83GHz
Billow	5.36	4.14
Circle Closing	3.32	3.13
Circle Opening	3.41	3.09
Cross Dissolve	3.51	3.34
Disintegrate	6.14	4.73
Fade In	2.31	2.32
Fade Out	2.30	2.28
Overlap	3.25	3.25
Push	3.43	3.26
Radial	3.35	3.29
Ripple	6.74	5.32
Scale Down	3.73	3.53
Warp Out	3.58	3.91
Wash In	2.43	2.47
Wash Out	2.35	2.39
Total	55.21	50.47

The Core Duo was slightly faster - the total for all of its transitions was about 8.5% lower than the iMac G5's time. 

The bigger performance differences come when looking at the Video FX render times.  These effects take anywhere from a few seconds, all the way up to multiple minutes to render, and can definitely bog down the creation of any movie project. 

iMovie HD Video FX Rendering Performance in Seconds (Lower is Better)	iMac G5 1.9GHz	iMac Core Duo 1.83GHz
Adjust Colors	75.62	48.62
Aged Film	30.43	32.44
Black & White	52.62	35.81
Brightness & Contrast	26.12	28.13
Earthquake	113.69	56.75
Electricity	78.47	54
Fairy Dust	151.69	58.63
Fast/Slow/Reverse	6.12	8.56
Flash	24.44	24.16
Fog	46.25	49.66
Ghost Trails	80.97	76.31
Lens Flare	61.12	46.22
Letterbox	26.94	28.75
Mirror	25.6	25.16
N-Square	31.13	32.63
Rain	45.6	39.75
Sharpen	35.75	43.25

The sample above is almost all of the effects that you can perform in iMovie HD; the exception being all of the Quartz composer effects, which were left off in the interest of time.  When the G5 and Core Duo are close, the G5 generally pulls ahead by a single digit percentage. However, when they aren't close, the Core Duo is usually ahead by at least 30%.  If you average it all out, the performance advantage translates into about 11% in favor of the Core Duo.  Once again, these tests are single-threaded, so there is no performance benefit due to the dual core nature of the Core Duo.