The PMO Center offers a Demand Analysis screen (pictured below), which is a way to see the overall portfolio feasibility at a glance.
The upper left dropdown allows you to view the demand feasibility in terms of demand (forecasted effort), shortfall, allocation, or % allocation (which is the default).
Remember that the effort forecast = Demand. The amount that can be filled is Allocation. The amount that can't be filled is Shortfall.
This also offers the same Optimization tools as on the Forecast tab. See Effort Forecasting for more details.
In the upper right, you can set your date range and granularity.