Hello @Reptorian,
It can create new layers, but that option doesn’t work.
Therefore it is a bug…
I have taken a glance at the Krita bug tracker and only a few reports of G’MIC are listed on there which is kind of strange since G’MIC is far more unstable on Krita compared to Gimp 2.8.10.
Yesterday [1], I have done a few quick tests comparing Krita 4.2 pre-alpha and Gimp 2.8.10. It does look like G’MIC 2.5.6 is faster on Gimp: only tested the Rodilius filter, which is multi-threaded, with the same jpeg 2.2 Mb image and settings.
With Krita it also looks like there are some feature not implemented in the G’MIC GUIs compared to Gimp, such as the option to import many layers at once e.g. for the Montage filter where this feature is vital. At present, Krita 4.2 alpha even crashes if you try to set this option in the G’MIC GUIs
Unfortunately, these missing options are not apparently listed on the Krita web-page and it is extremely difficult to figure them out (at least I was unable to find them personally…)