If you get an Nvidia GPU, you can use shadowplay (bundled free with Nvidia drivers). It uses the GPU more than CPU for recording gameplay so uses WAY less resource. an i5 and gtx 970 or above will play and record at 60fps 1080p.
Hell, with shadowplay I get 50fps record and play on high/ultra in most games at 1080p, and thats with an FX8370 and gtx 960 lol.
edit - forgot I put a vid of MGSV on youtube at 1080p 60fps with my cheap setup, for proof lol
MGS V: Lets play