CPU Multiple Tasks - Convert While Recording

I’m not the most technical person, so please excuses me if I not using a correct term. I recently setup a Plex Server along with a HDHomeRun Prime w/ FiOS Cable Card. It’s my understanding that it’s preferable (from a file size standpoint) to have recordings as H264. However HDHomeRun Prime saves files as MPEG2VIDEO in .MKV. I just came across the the option in the Live TV & DRV setting to “CONVERT VIDEO WHILE RECORDING.” As best as I can tell this seems to convert (in real time I think) my recordings and live TV to H264. I have read some people saying that using this option cam create artifacts in the recording or other issues. I have not seen this happen.

My question is, with “CONVERT VIDEO WHILE RECORDING” turned on, should I be concerned about “overworking” my CPU if, for example, I have all 3 tuners recording together and perhaps another pre-recorded show being transcoded and viewed? Thanks!

Server Info:
Mac Mini
MC815LL/A 2011
Core i5 2.30Ghz
4GB RAM