I split this topic in two so we don't pollute the 0.16 release topic at viewtopic.php?f=8&t=11557
in branch https://github.com/yorikvanhavre/FreeCA ... pref-pages
I tested making the Arch and Draft import/export-related pref pages load at FreeCAD start instead of workbench start. Although one has to load the resources files which contain the .ui files, it doesn't seem to slow freecad startup down. If needed, it will also be easy to split the resource files in two (one containing only the ui files needed at startup), to make it load even faster.
For the Part and Mesh import/export pref pages (IGES, STEP and Mesh formats), things are a bit more complicated, since they have part of their functionality in C++ code, and are bundled into PartGui and MeshGui workbenches, which we certainly don't want to load at FreeCAD startup.
A solution would be to remove them from the C++ code, and load them from the InitGui file, like python modules. This is possible if the C++ code doesn't do any fancy thing, I'll have a look.
Werner, if you read this, what is your opinion?