[FFmpeg-user] Is it possible to speed up merging-speed from HD to LAN?

[Christoph Gerstbauer]

Hello

I am working with ffmpeg over LAN.
I want to MERGE 2 files.
1 AVI with huffyuv and
1 WAV with pcm_s24le
to one file (AVI) with a video and a audio stream.

If I do this from HardDisk to LANshare it takes more time than a simple 
filecopy of both files to the same target.

1GBIT LAN:
Filecopy: 80 percent LAN speed
Merging: 25 percent LAN speed

https://cerebrum.noa-audio.com/noacloud/public.php?service=files&t=7b6808d2304afc89387ee183af862f60
On the left side you can see the filecopy- and on the right side the 
merging-lanload.

Is it possible to speed the merging up in any way?
Does the ffmpeg merger has an internal bottleneck (?)

command line:
ffmpeg -i inputfile.avi -i inputfile.wav -acodec copy -vcodec copy -map 
0:0 -map 1:0 \\lanshare\folder\targetfile.avi

Best Regards
Christoph