NOW, you have identified the bottleneck.
Everything is dependent upon this bottleneck. Recall the rate limiting step (RLS) in chemistry. This step is typically a catalyst or rare substrate. It's the process that S - L - O - W - S everything else down. In the ED, this may be: time to get a lab report, a 5150 bed, or the the on-call dialysis nurse.
Use a multi-perspective approach by including RNs, Techs, ICU docs, etc. to reduce the time it takes in the slowest step. This can be challenging, but will reap huge rewards.
Lather, rinse, & repeat.