How to optimize ffmpeg?

Question

Nginx

Yes:
OBS
Macbook Pro Retina i5, 8gb late 13
ffmpeg 2.8.3 + decklink Blackmagic UltraStudio
Mini Recorder Thunderbolt
from whether you leave the program itself on the desktop or turn it off)
The task is to get away from OBS as from software as such. The main claims are that it sometimes just closes on a whim, the second reason is that if problems with overload begin, the channel simply drops and there is no way to restart without pressing a button. The interface itself too. There was an idea to use ffmpeg directly, at least I think OBS uses it.
Here is the launch line that works properly.
/usr/local/Cellar/ffmpeg/2.8.3/bin/ffmpeg -f decklink -i 'UltraStudio Mini [email protected]' -c:v libx264 -pix_fmt yuv420p -r 30 -aspect 16:9 -g 60 -profile: v baseline -b:v 2100K -f flv -c:a libvo_aacenc -ab 64k -ar 44100 -ac 2 rtmp://
... the piece of hardware is pure RAW and its buffer is overloaded due to the fact that the processor does not have time to process the stream.FPS sags immediately 10-15) What can I upgrade in this request to reduce the load
ffmpeg output

ffmpeg version 2.8.3 Copyright (c) 2000-2015 the FFmpeg developers
built with Apple LLVM version 8.0.0 (clang-800.0.42.1)
configuration: --prefix=/usr/local/Cellar/ffmpeg/2.8.3 -- enable-shared --enable-pthreads --enable-gpl --enable-version3 --enable-hardcoded-tables --enable-avresample --cc=clang --host-cflags= --host-ldflags= --enable -opencl --enable-libx264 --enable-libmp3lame --enable-libvo-aacenc --enable-libxvid --enable-decklink --enable-vda
libavutil 54.31.100 / 54.31.100
libavcodec 56.60.100 / 56.60.100
libavformat 56.40.101/56.40.101
libavdevice 56.4.100/56.4.100 libavfilter 5.40.101/5.40.101 libavresample
2.1.0/2.1.0
libswscale
3.1.101/3.1.101 libswresample 1.2.101/1.2.101
libpostproc 53.3.100/53.3.100
Hyper fast Audio and Video encoder

Answer 1

0. OBS Studio
1. [email protected] x 4.5Mbit = no need to show 2.5Mb soap movie
-preset ultrafast, superfast, veryfast, faster, fast, medium, slow
https://trac.ffmpeg.org/wiki/Encode/ H.264
go from left to right through the parameters of the preset until you reach the load of the processor that is required
2. Buy a good capture card and encoder