Bug 489926

SUMMARY
When transfering files to a device/partition that needs elevated/root permissions, those transfers start fast but progressively slow down until they get extremely slow, sometimes around a few KB/s, when the device in reality supports much faster speeds.

Using a different file manager like Thunar to do the exact same file transfer between the exact same devices or partitions, using elevated privileges, the transfer is much faster, as fast as the devices can achieve, making it equal to a transfer that would be done with normal user permissions.

Dolphin also keeps asking for the root password every few minutes, pausing the transfer while it waits for the password. Makes it impossible to use dolphin for these type of transfers, because its so slow that it can take hours, but you need to constantly be staring into the screen to input the root password every few minutes or the transfer stops. Dolphin should maybe "remember" the password and not need to ask it again, at least during that file transfer, or while it itself is open with elevated privileges.

STEPS TO REPRODUCE
1. Open dolphin as admin / elevated privileges and inside it, navigate to a partition or device that needs elevated privileges to write into.
2. Copy a file from anywhere to that protected partition/device.
3. Notice the transfer starts fast but slows down to a crawl.
4. Every few minutes, notice dolphin constantly asks for the root password, and pauses the transfer while waiting for the password, even though dolphin itself was provided the password when it was first opened with elevated privileges. 

OBSERVED RESULT
Extremely slow transfer speeds and password popups every few minutes, stopping the transfer while waiting for password.

EXPECTED RESULT
Speeds at least equal to user-level privileges dolphin, and not asking the password constantly after it was already provided.

SOFTWARE/OS VERSIONS
Linux: 6.8.12-200 Nobara KDE
KDE Plasma Version: 6.0.5
KDE Frameworks Version: 6.2.0
Qt Version: 6.6.2