[Laminar]

I'm working on an iMovie project and started wondering which computer I should use for the final render. It's going to be a few hours of HD video so I figure picking the right computer could save me literally MINUTES of time.

Option 1:
27" iMac, mid-2010. i7-870 with 4GB of RAM

Option 2:
"Mac", i5-2500K with 8GB of RAM

Both have 1TB SATA hard drives. Both are running 10.8.4. The i5 may seem like the obvious winner due to its newer architecture and higher clock speed, but the i7 has more L3 cache and (the potential for?) hyperthreading. CPU-World benchmarks go either way depending on the test.

So which would render the video faster?

[P]

If iMovie is compiled to make use of AVX, the i5-2500K would be significantly faster. As it is, I think it wins anyway simply because it has a much higher non-turbo clock - 3.3 instead of 2.93. IME, Hyperthreading doesn't help in cases like this.

[Laminar]

I suppose there's no real downside to having a race to see which finishes first. Everything is being edited on a MacBook Air as I'm away from home for a month, but there's no way the MBA could render it in less than a couple weeks.