Yeah it depends how much memory the system has available. At least on my testing, speed seems to be increasing if the Nextcloud user upload directory is placed into ram
root@DietPi4:~# df -h | grep nextcloud
tmpfs 6.0G 384M 5.7G 7% /mnt/usb/dietpi_userdata/nextcloud_data/admin/uploads
root@DietPi4:~#
root@DietPi4:~# cat /etc/fstab | grep nextcloud
tmpfs /mnt/dietpi_userdata/nextcloud_data/admin/uploads tmpfs size=6G,noatime,lazytime,nodev,nosuid,mode=1777
root@DietPi4:~#
This way I was able to upload a 4GB file in around 10,5 minutes. 6 Minutes are spend to upload the file, rest was to assemble the chunks and to store it on disk.