cpu using is incrace each every hardware encoding like %50 gpu %50 cpu

Hello there
I use a DELL T7920 workstation, I am doing hardware encoding with the quadro m2000 graphics card. I’m doing video encoding with nvenc_264 with tvheadend program. the CPU is loading 60% of the time while it needs to fully process with the GPU. I did the cuda setup

±----------------------------------------------------------------------------+
| NVIDIA-SMI 390.30 Driver Version: 390.30 |
|-------------------------------±---------------------±---------------------+
| GPU Name Persistence-M| Bus-Id Disp.A | Volatile Uncorr. ECC |
| Fan Temp Perf Pwr:Usage/Cap| Memory-Usage | GPU-Util Compute M. |
|===============================+======================+======================|
| 0 NVS 315 Off | 00000000:73:00.0 N/A | N/A |
| 30% 38C P8 N/A / N/A | 145MiB / 963MiB | N/A Default |
±------------------------------±---------------------±---------------------+
| 1 Quadro M2000 Off | 00000000:D5:00.0 Off | N/A |
| 56% 39C P0 23W / 75W | 313MiB / 4043MiB | 5% Default |
±------------------------------±---------------------±---------------------+

±----------------------------------------------------------------------------+
| Processes: GPU Memory |
| GPU PID Type Process name Usage |
|=============================================================================|
| 0 Not Supported |
| 1 1723 C /usr/bin/tvheadend 302MiB |
±----------------------------------------------------------------------------+

PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
1723 hts 20 0 86,495g 1,282g 400752 S 563,0 2,1 2994:35 tvheadend
2805 root -51 0 0 0 0 S 1,0 0,0 5:07.51 irq/87-nvidia

There are 5 transcoding operations.
Why am I making a mistake in using the CPU too much. I fully appreciate the code as hardware with the graphics card. if we increase the number of encodig, the CPU is increasing in parallel