I'm not familiar with that game capture software, however when you record at 1920x1080 resolution, you will only be able to record at 30 FPS. If you try to record HD resolution at 60 FPS, you'll stutter. If you want to record at 60FPS, then you need to use "half size" which would be half of whatever resolution you are recording at.
If you are using an external hard drive, I'd make sure its a USB 3.0 hard drive as the slower the hard drive, the more open you are to stuttering. Also make sure to defrag your hard drive from time to time (DO NOT DEFRAG A SOLID STATE IF USING ONE), as this will help with recording.
If you are still noticing stuttering at 30 FPS full size (your current game/screen resolution) then you may need to change your graphic settings and set them lower. A lot of times you'll just have to experiment before actually starting a new series or starting to record.