backup is too slow, not usable

[TjrGithub]

• [ yes] I am running an official build of TWRP, downloaded from https://twrp.me/Devices/
• [ yes] I am running the latest version of TWRP
• [ yes] I have read the FAQ (https://twrp.me/FAQ/)
• [ yes ] I have searched for my issue and it does not already exist

mido:
3.3.0-1:

WHAT STEPS WILL REPRODUCE THE PROBLEM?

Install TWRP,
take a backup (with the options: enable compression, encryption with a random password)
wait

WHAT IS THE EXPECTED RESULT?

After an hour, the backup should be finished.

WHAT HAPPENS INSTEAD?

After an hour, the backup is still running. While backing up data, it seems to be especially slow, updating the files counter one by one every few seconds. It "feels" especially slow while the screen is locked.

ADDITIONAL INFORMATION

Unencrypted backups were fast with TWRP 3.2.3-2, so this must be either new or related to encryption.

/tmp/recovery.log: https://paste.omnirom.org/view/21f0dd14#UzCZXx4IsPW7vnPUTLpWPhUDSxepw68j
dmesg: https://paste.omnirom.org/view/e863c310#tgbUOj5kWr0XW9a7NVAcHTweO5zx5SvK

[bigbiff]

Hi, we will probably remove the encryption of the backup stream in an upcoming version of TWRP. Sorry for the inconvenience.

[TjrGithub]

Too bad. I was using encryption to plug the privacy leak created by carrying around unencrypted backups on a removable SD card.

[CaptainThrowback]

@TjrGithub

It's still a privacy leak, "encrypted" or not...see here: #817