OpenMP (
http://openmp.org/) is an API for parallel programming. It helps in developing multi-threaded code able to use multiple cores when doing heavy computation (which is often the case for image processing). I've recently started (3 days ago to be honest

) to add a lot of OpenMP directives into the G'MIC source code, and I have already very interesting speed gains for time-consuming filters. If you have a multi-core machine, the next 1.5.9.3 version of G'MIC will be probably very interesting for you.
For instance, on my 12x2 cores machines, I get roughly a x3.5 speed gain on the computation of the 'Dream Smoothing' filter.
as I've described it here :
https://plus.google.com/117441237982283 ... oshujYowPYFor some other operations, this can be even more.
This is of course adding an additional dependency to the OpenMP Library (so an additional .dll) for the plug-in, but this is really worth it.
Samj has been doing some compilation tests recently for Win64, and she confirms the speed gain as well.
1.5.9.3 is still in a 'beta' state, but it seems to be already quite stable. I will add more and more OpenMP directives in the future, so that 1.5.9.3 final should be even faster (on multi-core machines).