Add several thousands of prefixes into bgp table

Hey.
I’d like to add a few thousand prefixes into bgp table with a script:
#!/bin/vbash
source /opt/vyatta/etc/functions/script-template
configure
set vrf name client protocols bgp address-family ipv4-unicast network 49.127.0.0/16
set vrf name client protocols bgp address-family ipv4-unicast network 149.0.0.0/9

commit
exit
I prepared a file with 20k prefixes and run it. But it runs for hours with no plans to stop. Other question is - how long will it take to load the config after system reboot ?
Is it possible to do the job somehow?

This was intended just to simulate somehow the memory leak on the neighbor vyos regarding @ovallaste 's post

If it is for troubleshooting, I would use exabgp to load the 20k prefixes and feed them over bgp to FRR/VyOS.

Not sure if FRR likes it if you load that many prefixes that way.