So for my Databricks Workflows , i'd a job that was using Environment 3 of Serverless Compute with Performace Optimized as enabled , as we wanted quick execution of Job when triggered . There can be around 10-20 concurrent run , but noticed maybe of the job run stayed in queue even after other runs got completed . 

Also when i switched to Env 4 , so same job had no queue time , but had increased execution time .

So is there any documentation about how does different environment handle queuing , and concurrent runs?