Hi Markus,

First thanks for sending the logs.  I'm replying here so that others
can pitch in with their own suggestions.

The interesting parts of the old and new loaders logs are:

New OpenFlight plugin stats after optimization:

Stats after:
Object Type     #Unique #Instanced
Group           3357    8974
Transform       10592   10594
LOD             4575    16866
Switch          0       0
Geode           8981    26704
Drawable        9338    28964
Geometry        9338    28964
Vertices        508153  687961
Primitives      159927  215328

Old OpenFlight plugin stats after optimization:

Stats after:
Object Type     #Unique #Instanced
Group           3571    3572
Transform       26      28
LOD             16863   16866
Switch          0       0
Geode           19831   19855
Drawable        28910   28959
Geometry        28910   28959
Vertices        687680  687996
Primitives      210381  210460

--

The big differences lie in number of Transform nodes in the scene
graph with the new loaders vs the old loaders - 10592 vs 26, which is
obviously where the slow down is comming from.

I believe the new loader is generating scene graphs with a lot more
sharing of nodes, which breaks the flatten static transforms
optimization pass in osgUtil::Optimizer, so transforms that are
removed previously remain in the scene graph.

The sharing does mean there is less goodes and geometry in the scene
though, which is also echo'd by the number of geodes and geometry
being less for the new loader.  However, this clearly isn't sufficient
to overcome the downside of not being able to flatten the transforms.

To overcome this perhaps we need to duplicate the shared subgraphs. In
the Optimizer there is COPY_SHARED_NODES, which isn't used by default.
I'll try it on the flight databases I have here and see if it
succeeds in allow the flat static transform to work.

Should just need to do:

 export OSG_OPTIMIZER="DEFAULT COPY_SHARED_NODES"
 osgconv myfile.flt myfile.ive

I'll do some testing at my end and see what I come up with.
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