AC works but is not very cold. How to troubleshoot?

The AC in my 2009 blows about 58F when it's 85F outside. I put gauges on the AC and it shows a little over 200 on the high side and about 40 on the low side. I do not see any bubbles in the sight glass. The exterior of the condenser seems clear of crud. The cabin filter is new, and there's plenty of airflow.

That performance seems rather lame... Without anything grossly obvious, what are the next steps to diagnose this?

Cheers,
Doug