Currently there are 2 command line parameters available you may try out.

-Jmaxheap
By default FireCapture will be started using a max heap size of 1GB. You may try to increase this using the -Jmaxheap option. It depends on your system how much memory the Java VM will be able to allocate so you need to setup this value by try and error. I consider anything above 1.5GB as poor luck ;-)
You need to setup the value in Bytes!  e.g. if you want to use a max heap size of 1.2GB (=1.2*1024*1024*1024=1288490189) create a shortcut with the following command line:
FireCapture.exe -Jmaxheap=1288490189

camera
You can directly setup the desired camera interface using the camera option. This is especially handy if you have two different cameras you want to start directly. So in such a case just create two shortcuts where you specify the proper camera interface number, e.g. for running a PGR cam directly use:
    FireCapture.exe camera=3

Please use one of the following numbers to directly setup the interface:
    0 -> search for any supported camera
    1 -> Basler Firewire (Pylon v2.3)
    2 -> Basler GigE (Pylon v2.3)
    3 -> Point Grey Research (FlyCapture v2.2)
    4 -> The Imaging Source (IC WDM TIS driver)
    5 -> Allied Vision (Universal Package v2.1)
    6 -> NET FOculus (FOcontrol v4.0.5.1)
    7 -> WebCam (Windows DirectShow)
    8 -> QHY CCD Camera (IMG* driver)   (optional package !)
                                        

The main setup and configuration of FireCapture will be controlled by its configuration file FireCapture.ini and most of the entries there are configured using the Settings dialog. The following entries are the list of hidden switches and may be configured manual if needed:

useFlea3SickMode
default: true
Some of the very first Flea3 models had some firmeware bugs preventing to start the camera properly. With the help by Anthony Wesley I added
some patches into the FlyCam.dll to overcome this. With setting this entry to false you can skip these and try if your Flea3 is still working.

useExtendedGain
default: true
By default FireCapture starts your Point Grey camera using an extended gain range (see Control for details). Some of those cameras (mostly CMOS) don't support this and FireCapture will hang while initializing the camera. For that case you need to set "useExtendedGain=false"

supportQHYCamera
default: false
QHY CCD camera support is available as optional package. Before running your QHY CCD camera you need to set "supportQHYCamera=true"  after you installed the QHY CCD package. 

filterWheelScript
default: not set
If you have a motorized filter wheel you can specify a script file which will be called after every filter change. The parameters for handed over to the script will be filter index and filter name, e.g. if you have set "filterWheelScript=myFilterScript.bat" and you switch to the first filter entry (e.g. UV) FireCapture will call "myFilterWheelScript.bat 0 UV". You should place the script file into the main directory of FireCapture. See also the Obsolete FilterWheel interface.

directShowUseMono=true
default: false
If you're using the DirectShow interface in FireCapture the resulting data will be stored as color video by default. In case you have a modified monochrome WebCam (or any other monochrome camera) you can set "directShowUseMono=true" and FireCapture will store Y800 format with 1/3 of the size.

directShowMaxWidth
default: 640
If you're using the DirectShow interface in FireCapture and you're running a camera supporting a max width other than 640 you can set the max width here.

directShowMaxHeight
default: 480
If you're using the DirectShow interface in FireCapture and you're running a camera supporting a max height other than 480 you can set the max height here.

syncFPS
default: true
For TIS DMK/DBK cameras only: If enabled the frame rate will be synchronized with the shutter speed. See Control for details.

customROI
default: none
Here you can insert your favouorite ROI sizes which will be available as popup menu if you right-click over the width/height fields
in the Image panel. Avoid blanks and use the following sytax. e.g. "customROI=300x300,380x380,400x400"