I need to stich a lot of geotiffs, located on an S3 storage into a big geotif.

Currently I using the following commands

```
gdalbuildvrt -input_file_list filelist.txt -overwrite /tmp/output.vrt
gdalwarp -co COMPRESS=LZW /tmp/output.vrt -overwrite /tmp/result.tif

```

works but painfully slow. we are dealing with around 5-11k geotiffs on S3.
How can i perform this in parallel. CPU and network is neither near a limit so I assume it is running in a kind of "one thread mode".
I saw there is a multi option for gdalwarp but nothing for gdalbuildvrt.

thx for your help!