make promises parallel

[wlgs]

Hey

what was done

• reduced delays
• made promises run in paralell (for me it reduced download time from 2mins to 9seconds)

[nadimkobeissi]

Thanks, this is a good improvement.

However, I'm intentionally not downloading things in parallel and adding a small delay.

• We don't want to spam Google servers.
• You can afford two wait two minutes.