Check the BIOS/UEFI. Many motherboards come in 'automatic' mode, which may split channels. You may have to go in and set the PCIe mode to x16/x1, if it defaulted to x8/x8 (splitting).
Also, as the Xbone app is a Metro app, the only way to capture it at present is with a Monitor Capture. This kind of thing is also why recording the app is a workaround, and NOT a replacement for a capture card.
As an aside, disabling Aero was a workaround for Windows 7 monitor capture ONLY due to MS not allowing access to certain parts of the architecture. It was fixed in Win8 and up. Also, a workaround was found for Win7. There are only a very few reasons to disable Aero under 7 any more, and they're very uncommon scenarios.
Xsplit's screen grab is just a monitor capture with a built-in crop.
I'd be MUCH more concerned that you're trying to stream/record at 1080p@30 on 2500kbps, on an AMD FX6300 on the Veryfast preset. That ain't gonna work.
If you're trying to record locally only, follow the HQ Local Recordings guide:
https://obsproject.com/forum/resources/how-to-make-high-quality-local-recordings.16/
If that's the case, it's entirely unsurprising that you're getting framerate issues as you're DRASTICALLY overworking your CPU. It just can't handle the settings you're trying to use. My guess is that your framerate is going to crap because the FX6300 can't handle real-time 1080@30 video encoding on that preset alone, much less also decoding the video coming from the Xbone then
reencoding it into the video file.
Follow the HQ Recording guide,
all the steps. It should reduce your CPU usage significantly, and if overloading is the issue (along with the PCIe bandwidth correction in the UEFI/BIOS) it should record smoothly. Won't help with streaming though, but it will show the next step to take in troubleshooting.