Nextcloud Office opening simple documents extremely slow

I just added another hard drive, /tmp is now on EXT4 fs. And Nexcloud behaves exactly same - still creates wierd file with questionmark…

But! ODS and ODT files are now opening much faster, even if hard drive mounted to /tmp is several times slower rotating magnetic drive, not SSD.

For comparison:

hdparm -tT /dev/nvme0n1

/dev/nvme0n1:
Timing cached reads: 34792 MB in 2.00 seconds = 17419.64 MB/sec
Timing buffered disk reads: 9172 MB in 3.00 seconds = 3056.71 MB/sec

(on this drive is space for linux, nextcloud files and application)

hdparm -tT /dev/sdd

/dev/sdd:
Timing cached reads: 34612 MB in 2.00 seconds = 17329.09 MB/sec
Timing buffered disk reads: 388 MB in 3.00 seconds = 129.24 MB/sec

(on this drive is /tmp)

So Nexcloud behaves differently with different filesystems on /tmp. For some reason have problem with much modern BTRFS in comparison with EXT4.

Why?