Low decoding speed when editing from NAS via SMB

[M4T]

Dear Avidemux community,

I use a NAS to store video files, which is directly connected to a workstation for cutting these files.
But when opening a video from the NAS at the workstation with Avidemux the decoding speed is super slow - it takes 15min instead of <1min.

These are more or less the average decoding speeds for comparison:
~200 fps from NAS via SMB (1GBit)
~400 fps from NAS via SMB multichannel (2x 1GBit)
~5000 fps from workstation via internal HDD
~15000 fps from workstation via internal SSD

NAS: QNAP NAS TS-853A with latest firmware
Video files: AVI, H264, 1920x1080, size 3-5GB
Workstation: Win10 Pro, i5-6500 CPU @ 3.20GHz, 16 GB Ram
Avidemux version: 2.8.1 Release

I guess getting a NIC with 4x 1GBit ports at the workstation for SMB multichannel will also not increase the speed by ~10 times.

Is there any possibility to increase the decoding speed by reading the files from the NAS to at least 5000 fps?

[eumagga0x2a]

Video files: AVI, H264, 1920x1080, size 3-5GB

Storing video streams compressed with codecs, which need presentation timestamps to be available, in a container that does not support presentation timestamps must stop, once and for all.

These are more or less the average decoding speeds for comparison:
~200 fps from NAS via SMB (1GBit)
~400 fps from NAS via SMB multichannel (2x 1GBit)
~5000 fps from workstation via internal HDD
~15000 fps from workstation via internal SSD

Do you imply that storage I/O is the bottleneck and not the CPU performance? 15000 fps sounds entirely out of this world for me, I measured at best ~7000 fps when decoding a 1280x720 H.264 source stored on an internal NVMe SSD on a state-of-the-art high-end CPU using 16 threads, on a CPU that plays in a different league than an old 6gen i5. The average reading speed for the file was ~29 MiB/s, orders of magnitude lower than the performance limits of the storage.

The general advice would be not to use Avidemux with non-local files, but the figures you provide look very strange nevertheless.