LE doesn't have htop
Install the LE addon 'System Tools' and 'htop' is ready
the 224% CPU seems about right for these slower SoC's. Recording 3 streams and watching one is much less CPU intensive which is probably a better use case. TVHeadend on the RPi3 might be a little lighter
I no longer know if you are talking about NextPVR or LibreELEC. 224% CPU is certainly excessive and I would say impossible for LibreELEC. If this happens with NextPVR then the thing to do is avoid any type of transcoding to recover low throughput values. Recording three streams simultaneously can be very taxing when done on USB flash drives, but not on internal system storage.