Kazrog plugins use high resolution internal oversampling, and with some configurations of FL Studio may require a fixed buffer size to avoid stuttering. Contrary to FL Studio's dialog, this is not a bug, but a feature.

FL Studio 20:

Use the settings shown below in the plugin settings window (enable "Use fixed size buffers"):

 

Earlier FL Studio versions:

Use the following settings:

  1. Enable "Use fixed size buffers"
  2. Uncheck "Allow threaded processing"
  3. For FL Studio 11 - in "Options" menu
    - Uncheck "Use block size as buffer size"
    - Check "Use host block size"
  4. For FL Studio 12 - in "More" menu
    - Uncheck "Process maximum size buffers"
    - Check "Use maximum buffer size from host"