Innodb bulk load : high IO, crashes on Linux, OOM on Linux, as tested with LOAD DATA INFILE

Found by accident, trying to understand why sysbench loads its data faster than
mariadb-import --parallel. Mostly likely present before 11.6, did not try.

TLDR: for me, Bulk load turns out to be 1.5 times slower (on fast NVME), and more than 15 times more IO intensive.
I tried on Windows, and it is just slow, and this case is below

I tried on Linux, hoping that maybe BULK relies on temp directory being in memory, but got crash (tmpdir exhausted), or when
I allowed tmpfs to be 32GB (whole memory), then server process got killed, probably Linux peculiarity the OOM killer.
If tmpdir points to persistent disk, effects are about the same on Linux as they are on Windows

Below, my test case:

Step 0 - server parameters

We run load "in-memory", and both bufferpool and redo log will be larger than the IBD file.

[mysqld]

innodb_log_file_size=20G

innodb_buffer_pool_size=20G

innodb-buffer-pool-load-at-startup=OFF

innodb_buffer_pool_dump_at_shutdown=OFF

innodb_stats_auto_recalc=0

Step 1. Using sysbench, load a single table with 50M rows (~11GB ibd file)

sysbench oltp_read_write --mysql-user=root  --tables=1 --table-size=50000000 --threads=1  prepare

Elapsed time (seconds): 273.673
Process IO Read Bytes : 14387837038
Process IO Write Bytes : 19291281550

Step 2: backup sbtest.sbtest1 table

mariadb -uroot -e "select * into outfile 'C:/work/sbtest1.data' from sbtest.sbtest1"

Elapsed time (seconds): 36.482

restart server

Step 3: Load this data again, without bulk optimization

mariadb -uroot -e "truncate sbtest.sbtest1; load data infile 'C:/work/sbtest1.data'  into table sbtest.sbtest1"

Elapsed time (seconds): 240.996
Process Read Bytes 9916879781
Process Write Bytes 15149246158

Restart server again,

Step 4: Load the same data once more, with bulk optimization (enforced by setting unique_checks=0,foreign_key_checks=0)

mariadb -uroot -e "truncate sbtest.sbtest1; set unique_checks=0,foreign_key_checks=0, load data infile 'C:/work/sbtest1.data'  into table sbtest.sbtest1"

This is the step that is very slow, pegs the disk at ~1GB reads and writes, and this is where it crashes on Linux, if /tmp is memory.
When it is slow, CPU is at about 3%, busy with some reads and writes to temp. files.

Elapsed time (seconds): 371.664
Process Read Bytes: 167433868189
Process Write Bytes: 170475124430

Compare execution times and IO usage from Step 3 (without bulk) and Step 4(with bulk) , and sysbench "prepare"