I'd also say that with an i5, 720@60 is going to be really pushing what it can provide, in terms of video encoding. Backing it down to 720@45 would probably give you a bit more breathing room... the i5 is a great processor if you're just gaming. But it doesn't have the grunt needed to game AND perform real-time video encoding in true HD, at high framerates, with good quality.
If your setup is compatible with QSV (Intel QuickSync Video) you may consider turning that on; it's a quality hit, but will drastically reduce your CPU utilization. You need a compatible CPU, motherboard, and may need to enable QSV in the BIOS (we've had a few people that hadn't done this last step and couldn't figure out why it wouldn't work).
But as noted, QSV will not produce image fidelity as high as the non-QSV encode.