The standard ‘out-of-the-box’ system will perform reasonably for many companies. There is always a need to test the performance and tune the system to your requirements.
If your implementation uses inventory, and if you are using batch and or serial numbers, then you might find your inventory performance to be sluggish. You might want to look at your indexes on the tables InventDim and InventSum. These tables are used in almost every query when involved with inventory.