Get your top wait type with sp_BlitzFirst @SinceStartup = 1
| If your top wait type is | Then use @SortOrder = |
| CXPACKET | CPU and Reads separately |
| SOS_SCHEDULER_YIELD | CPU |
| THREADPOOL | CPU |
| LCK_** | Duration |
| RESOURCE_SEMAPHORE | Memory grant |
| PAGEIOLATCH_** | Reads |
| WRITELOG | Writes |
Database Blog 