Drone cloud runs on donated infrastructure and we have fixed capacity that allows us to run 200+ concurrent pipelines on bare metal instances. However, we sometimes experience high build volume which causes congestion and results in long wait times (during these wait times your build is in a pending state).
As @nemequ mentions, the best option to guarantee short queue time is to install Drone on your own infrastructure. The Works on Arm program donates Arm machines to open source projects, and you can also get free open source credits for AWS which also supports Arm. There are also plenty of providers that you can use for low cost amd64 machines.