Some more bugs fixed.
macOS builds are available now too. Check the 4.0.0 changelog for the macOS specific new features.
v4.0.3 changelog:

• BUGFIX: Add height padding to the transfer list icons. Closes #7951. (sledgehammer999)
• BUGFIX: Allow to drag-n-drop URLs into mainwindow to initiate download. (Chocobo1)
• BUGFIX: Fix crash when fitlering search results. Stable sorting is removed. Closes #7952.(Chocobo1)
• WEBUI: Fix missing qbt logo on login page in webUI. Closes #7953. (Chocobo1)
• WEBUI: Add check to avoid type error after logout. (Chocobo1)
• WEBUI: Use POST for logout command. This is to avoid browser being smart to prefetch the link then logging out the user. (Chocobo1)
• WEBUI: Fix WebUI is not reachable via IPv6. (glassez)
• WINDOWS: Disable the "?" help button in all dialogs on Windows. Closes #7365. Requires Qt 5.10. (Chocobo1)

I had some problems with 1qBittorrent and then I switched back to utorrent. I found that qBittorrent can't seed for private trackers. Same torrents were uploading on utorrent but not on qBittorrent. Was this a bug or just happened to me?

and i guess they will never fix the download speed, it doesn't use full bandwidth but clogs the connection for all the other applications
no full speed and no browsing while qbittorrent downloads

qBittorrent is probably the best torrent client out there.Never had problems with it.I used many clients over the time...
Also you have a bandwidth limiter option with just a click...check Options ---> Speed.