Final Cut Pro Performance Tips: RAM & Mac Pros
Posted by Michael Curtis
Final Cut Pro: For best performance on Mac Pro, install memory in risers symmetrically

Final Cut Pro's performance benefits from symmetrical RAM configurations on Mac Pro.

The Mac Pro comes with two memory riser cards, each with four DIMM slots. With a total of eight slots, you can add up to 16 GB of memory.

To achieve optimal performance when running Final Cut Pro, memory DIMM pairs should be installed evenly on both risers.

Click the above link to see the chart of the various RAM configs they recommend. However,

Maximum memory usage in Final Cut Pro is 2.5 GB. Note, that is max usable by FCP is 4GB total.

Explanation follows from second article:

Why can't Final Cut Pro use more than 4 GB of RAM?

Mac OS X is, at present, a 32-bit addressable operating system. This means that any single program running on the computer can take at most 2^32 bytes, or 4 GB, of memory. Final Cut Pro is subject to this ceiling just as any other program would be and is restricted to allocating no more than a total of 4 GB of RAM.

Why can't I allocate more than 2.5 GB of RAM to Final Cut Pro?

The memory available for allocating in the Memory & Cache tab of the System Settings window includes memory directly used by Final Cut Pro, but the program loads many other frameworks, libraries, and drivers, which may also allocate memory. Although this memory isn't directly allocated by the program itself, the allocation still falls into Final Cut Pro's address space and contributes to the 4 GB limit. Final Cut Pro reserves 1.5 GB of RAM for these frameworks, libraries, and drivers and so only allows a maximum of 2.5 GB to be allocated by the user.

Therefore, except for when you're going to run multiple applications (and there are plenty of other apps you might want open simultaneously), huge gobs of RAM for FCP isn't going to necessarily help things move briskly.

If you have a large project, such as for a feature film, my usual advice:

1.) break it into reel size chunks, no more than about 22 minutes per chunk (can be small as you want)

2.) If possible, keep each reel its own project (docs this is harder due to shared bins etc.), and for speed's sake only assemble the whole thing into one project when you have to/need to and make that a new project, not dumping all reels into one of the reel's projects. But that gets into the whole other production thing...

For more on working with Final Cut Pro/Final Cut Studio 5.1.2, read this article from the other week, it is a compendium of FCP 5.1.2 issues.

-mike

PS - FCP 5.1.2 also has some nice enhancements to tell you what is going on - check out this screen grab I got while doodling with 5.1.2 on my MacBook trying to play 6 tracks of DVCPRO HD from the internal drive (knowing it would fail):

It is so very, VERY nice to get specific advice on what's going wrong, and better yet to get specific instructions on how to fix it.

{Beer Ad Voice}
Here's to you, Mr. Warning Dialog Detail Improver, for all the help you give us. Have a tall cold one on us.
{/Beer Ad Voice}

Frankly, if this is what they consider an x.x.2 release, I think they must have beeeg, beeeeeeeeeeeg changes in mind for NAB next year - if they had wrapped the 5.1.1 and 5.1.2 changes into a new version and called it 5.5 and charged $200-$300 for it, they could have gotten away with it. But they didn't - so I figure they are swinging for the fences for the next version....

Posted by: Mike Curtis on the HD for Indies Blog.