[Gimp-developer] Ways to improve Gimp 2.9 performance

[Elle Stone <l elle stone gmail com>]

When working with full-size camera files (3906 X 2602 px, not large
compared to more recent cameras), Gimp runs at 100% CPU. Painting a
brush stroke takes forever, my system swap drives fill up completely,
etc. And yesterday Gimp filled up 15GB's worth of empty space in my
home directory, leaving mere kilobytes of empty space - I'm not sure
what file was taking up all the space, but it disappeared as soon as I
closed Gimp.

So I'm seeking advice on how to improve performance. I broke the
question into 3 parts:

1. Hardware
2. Configuring Gimp
3. Image size, type, precision

1. Hardware

What are the recommended (not miminal) system specifications for
running Gimp? My system specs are:

*1 single-core 2.6 GHz processor (the system board will take 2
processors, but only single core)
*4GB ram; the system board will hold 16GB
*256MB nvidia GeForce 7600 GTgraphics card
*4 sata hard drives (I don't think I set the sata drives correctly to
take advantage of their fastest write speeds)

Short of building a new computer (not going to happen!), what else can
I do to improve Gimp performance? Which hardware upgrade(s) might give
the most performance improvement for the least amount of money?

*We can replace the single processor with two slightly faster
processors. Will two processors make a difference?
*Will reconfiguring the sata drives to use their fastest write speed
help? How much does write speed matter?
*Are there figures for optimal RAM, other than "as much as possible"?
*How much does the GPU affect Gimp's processing speed? Would upgrading
the graphics card help? If so, how much of an upgrade would it take to
make a perceptible difference?
*Other possibilities?

2. Configuring Gimp:

I'm running 64-bit openSUSE 12.2  with the Icewm minimal window
manager. I set the Gimp tile cache size to 3GB, and I've followed much
of Aaron Paden's Gimp setup advice:
http://gimp.1065349.n5.nabble.com/gimp-2-8-prohibitively-slow-td34425.html

Given that my computer has four physical hard drives, is there an
optimal way to allocate GimpSwap, Gimp temporary folder, the location
of the image files I'm working on, system swap, and etc? Here is my
current arrangement:

*HD1: all system folders, including the "tmp" folder that Gimp uses
(Preferences/Folders). Also my home directory and all the Gimp
configuration files are on HD1.
*HD2: The GimpSwap (Preferences/Folders) is on this drive (along with
other stuff, of course)
*HD3: There is a 3GB system swap partition on this drive. Also this HD
is where any images that I'm editing with Gimp are located.
*HD4: There is a second 3GB system swap partition on this drive.

*Would it help if I add a third system swap partition on the second
hard drive? Or move the image being edited to the drive that doesn't
have a system swap partition?
*Does it matter how many dockers are open?
*Does it matter how many system fonts are installed?
*Would it help if the Temporary Folder and/or the GimpSwap had their
own partition (not a whole separate drive, but a separate partition on
an existing drive), instead of just their own folder? Should the
Temporary Folder be on a drive separate from the Gimp configuration
files? What are these two folders used for?
*Anything else?

3. Image size, type, precision

Short of working on smaller files, what else affects how much
processing power Gimp needs? Specifically,

*Does it make a difference what precision is used? 32-bit floating
point vs 16-bit integer?
*Does it make a difference if the image is grayscale rather than RGB
(one channel rather than 3)?
*Does the total number of layers, masks, and/or alpha channels matter?
Or is it just the overall image size in pixels?
*Anything else?

I know Gimp 2.9 is a work in progress and likely things will get
faster as times goes on. But in the meantime, any advice on how to
improve performance would be greatly appreciated.

Kind regards,
Elle Stone

-- 
http://ninedegreesbelow.com - articles on open source digital photography