If you have a somewhat recent Nvidia card you could try just using shadowplay functions, that could either start recording on a button push, or you could use the "shadow" feature for having the last few minutes saved, you know great for when something cool happens.
But that's only for Nvidia, dunno about AMD, I also find the controls a bit simplistic, and if you forget you started recording it will easily make a 20gig file after a while, I very much recommend having a large harddrive to store these on, DO NOT USE OS'S SSD !
Shadowplay can also stream directly to twitch and a few other services.
An option I'm playing with a little bit on the side now, with much more configurability (and free of charge) is the
open broadcaster, it's mainly for streaming so it starts off being quite highly compressed but all these things can be tweaked as you feel, and it doesn't have to stream it can simply record as well.
This also includes the same "save the last few minutes" feature as shadowplay has so it is nothing special, only in the OBS they call it replay buffer which is more descriptive to what it actually is.
But as for degrading your gaming experience as you play, it all depends on your machine, this is after still as resource intensive as it is.
For higher quality recordings shadowplay is probably easier on the system, but it could have a very high buy in since this is a GPU feature.