XSplit VCam uses your GPU resources by default. If you wish to use your CPU's processing power instead, click the menu icon at the upper left corner of the app. then select Settings. This will open the XSplit VCam Settings menu to the right.
XSplit VCam's Hardware acceleration is normally set to Automatic. Disabling this will allow you to set your Primary Hardware Acceleration to utilize your CPU instead.
If you instead want to keep using your GPU for XSplit VCam's Hardware Acceleration, but would like to reduce the GPU usage still, then changing the Quality to Standard (the lowest setting) might help.