Qbittorrent slow downloads ONLY on native Linux packages. AppImage works fine.

[KierPrev]

qBittorrent & operating system versions

Qbit 4.5.2
Archlinux/Ubuntu/Fedora, pretty much all distros except the older ones like Ubuntu LTS and Debian.

What is the problem?

All the native Linux versions have slow download speeds (around 100 Kb/s), but the AppImage versions download just fine.

Steps to reproduce

No response

Additional context

No response

Log(s) & preferences file(s)

No response

[thalieht]

No comparison of libraries used by qBt mentioned so i'll tag this as invalid until then.

[KierPrev]

AppImage libraries: (Works fine even on 4.5.2)

Native version with slow downloads:

The same behavior is observed in versions 4.5.2, 4.5.1, 4.5.0, 4.4.5... And more.
I think the last version that downloaded fine, was the 4.3.9.

[xavier2k6]

No comparison of libraries used by qBt mentioned so i'll tag this as invalid until then.

Another reason to make these qBittorrent & operating system versions an actual requirement in bug report & feature request templates especially now there are 2 versions of libtorrent & Qt........

[glassez]

Another reason to make these qBittorrent & operating system versions an actual requirement

Isn't that what it is?
How can we influence users not to ignore all these fields? Maybe blindly delete all incomplete Issues?

[Kolcha]

are downloading to HDD (exactly, HDD,not SSD)?

recently I also experienced very slow (up to 1 MB/s instead of ~15MB/s) download speeds to my external USB HDD.
was very surprised to see that, just because not so long time ago I downloaded the same too popular torrent using another torrent client (not libtorrent-based) to the same drive (content was deleted accidentally).
I used latest qBittorrent 4.5.2 (Qt5, lt 2.0) on Windows 10. I noticed very high HDD I/O (it was busy all time, like writing something very big (file I downloaded was ~35GB). "preallocate disk space" option was turned off. I tried to change "disk I/O type" in Advanced settings (just because I know and experienced some issues related to this in past), nothing has changed.
so, decided to try the same Qt5-based qBittorrent 4.5.2 but based on lt 1.2 - and I got normal speed as expected (almost the limit of my connection, torrent has many seeds), and no very high I/O activity.
information above (AppImage qBittorrent is based on lt 1.2, but native packages are based on lt 2.0) also similar to my observations. maybe something is wrong with lt 2.0...
I didn't report my observations anywhere, just because I didn't make any more research on it, and hard drive I used is too far to be good and it is behind no-name chinese USB-to-SATA chip with unknown capabilities.

[xavier2k6]

Isn't that what it is?

It is........to a degree & hence why we have some shortcomings like above

How can we influence users not to ignore all these fields?

I believe by making each field an actual requirement......it forces the user making a report to put in the requested info.

Anyway....this is going off-topic, will see what I can come up with PR wise.

[KierPrev]

are downloading to HDD (exactly, HDD,not SSD)?

Yes, but with the AppImage version, there is no such problem with slow downloads. It has something to do with the libraries.

I've already tried it on different machines, different networks, and different Linux distros.
The problem is exactly the same. Native is slow. AppImage is normal.

[stalkerok]

Don't use libtorrent 2.0.x and you'll be fine.

[KierPrev]

Don't use libtorrent 2.0.x and you'll be fine.

I don't know what that is, or how to change it. I'm just a user.
For the moment, I will stay using the AppImage version.

[Kolcha]

Yes, but with the AppImage version, there is no such problem with slow downloads. It has something to do with the libraries.

according to your screenshots, AppImage version uses libtorrent 1.2.18 (aka "lt 1.2"), so this is the same as in my case with Windows.

I didn't try to download anything to my HDD from Linux to confirm the same behavior, just because it is bad idea to write to NTFS from Linux, especially in case of such excessive random I/O as torrent clients may do. also it seems I miss something required to run AppImages in my system... none of apps I tried are able to launch...

[JimmyAx]

It is working fine for me with the native Debian package.

Debian 12 (bookworm, testing)
qBittorrent: 4.5.2
Qt: 5.15.8
Libtorrent: 2.0.8.0
Boost: 1.74.0
OpenSSL: 3.0.8
zlib: 1.2.13

[luzpaz]

Is there an upstream ticket(s) that are related to performance tweaking that we can reference ?

[stalkerok]

These problems will always be there, since this is an lt2.0 problem and there have been complaints about speed for a very long time. arvidn/libtorrent#6561

[luzpaz]

Thanks for the upstream tricket!

This ticket then needs a libtorrent label and an upstream label

[RENANZG]

disable file explorer thumbnails worked for me

[KierPrev]

disable file explorer thumbnails worked for me

What 👀
It's like "oh my wash machine doesn't work" "Well, just disconnect your printer"

[RENANZG]

disable file explorer thumbnails worked for me

What 👀 It's like "oh my wash machine doesn't work" "Well, just disconnect your printer"

So, depending on how your thumbnails are set up, every second you download a torrent movie a thumbnail (which can be quite large) is created. Well, if you are downloading a lot of movies directly onto a pendrive (on a usb 2.0 port for example) then you might run into problems. "Well, just disconnect your printer". Not all logical reasoning is "plausible" ;).