[Gimp-user] Layer groups seriously broken - huge resource hog

[BWK <forums gimpusers com>]

I love Gimp. I started using it about a year ago and it is the second most used
piece of software on my computers. I often use it on two of my computers at the
same time. I do stuff with it mostly with aerial photo mosaics up to 500
megapixels - aerial photo tiles joined together with other aerial photos
overlaid over the top of them. With the new unified transform tool in Gimp 2.10
an aerial photo overlay can be completed in one step of transformation thus
maximising the quality and speeding up the work. The software is brilliant for
this.

Nevertheless there seems to be significant shortcomings in the implementation of
layer groups in Gimp. I started using them because I had a lot of layers in my
projects and I wanted to keep everything tidy. But as my projects have grown, I
have found that layer groups are a huge waste of resources. With the biggest
project, the file size of the project doubled from 4 GB to 8 GB when layer
groups were used, with exactly the same layers. Part of creating these aerial
photos is to split them into tiles to be loaded into a GIS for mapping. This
requires resizing the canvas to crop the boundaries to a tile boundary and then
exporting the tile out as a JPG. Most of these tiles are only 4800x7200 pixels
that should not really be a problem for the computer. But with layer groups it
takes about 15 minutes to do the canvas resize with the disk constantly
churning. Without layer groups it only takes about 15 seconds. The export itself
is much faster with far less disk churning as well.

I only discovered this by accident when in one of my projects Gimp constantly
crashed when saving the project as soon as I added more than three layers to a
layer group. Obviously Gimp is broken in that area (and doesn't throw any kind
of error message or exception either, it just quits) but the result of having to
take out the layer groups I was putting in and working without them has had the
unexpected benefit of a huge time saving after allowing for a lost day trying to
work out what the crashing was about.

If this feature is going to be any good in Gimp in the future the implementation
of it needs serious attention.

-- 
BWK (via www.gimpusers.com/forums)