The option in the plugin preferences to "Keep BBW Open" is used to keep bbw4.exe running the entire time that the plugin is being used. By default, this setting is turned off which means that each time a user opens a BBW Picker (ie: Style picker, RT picker, etc.) bbw4.exe is closed and then reopened. This mainly helps with ensuring that the picker window is on top of all other windows but if a user finds that it takes a long time and the boot up times are not optimal then it can be improved by turning on this setting. This option however does not effect actual render times in the plugin.