Very long shader linking time with NVidia GPU
When you modify the settings of a big combination of effects with modifiers (particles noises...), some NVidia driver made Smode waiting more than one minute the shader linkage before displaying the new content settings.
If this behavior occurred with your NVidia GPU, first, try to update to the last NVidia driver version.
If the problem persist, quit Smode, go to the NVidia preference panel and deactivate Shader Cache like this:
Then try to cleanup manually the remaining NVidia shader cache files located in this folder:
After this operation, Smode shader linking time should return to the normal.