There are two known issues that sometimes causes the optimizer to run slowly.
The first issue is that if you are selecting or deselecting players from the Available Players Table with Auto-Team Stack or Exclude Opposing Defense turned on, the update calculation for the new list of Available Players takes a long time. As a workaround, try shutting of Auto-Team Stack and Exclude Opposing Defense until you are close to a situation where you might not be able to build a lineup from the available player pool. Then turn these back on to finish making your final selections.
The second issue is a known issue with the optimizer that sometimes causes it to peg the server CPU usage. This is not a load related issue, and happens most often in the very early morning. However, it can happen in the afternoon also. This results in slow performance.
ASL is working to identify the core reason for this issue and has set server alerts to let us know when it occurs.