Your backup job is green, but is every database in it? Here is a read-only way to find the ones missing from msdb history.
Unstable Queries: Finding Wide Duration Swings in Query Store
Find unstable queries with Query Store duration spread, weight averages, and separate plan changes from waits and parameter effects.
Signal Waits: Telling CPU Pressure From Slow Disks
Measure signal waits over an interval, compare scheduler queues and file latency, and separate CPU scheduling pressure from storage delays.
Running, Runnable, Suspended: The Life of a Query in sys.dm_exec_requests
Read running, runnable, and suspended SQL Server requests, inspect task states, and compare scheduler queues before diagnosing CPU pressure.
SQL SERVER – Finding Last Backup Time for All Database – Last Full, Differential and Log Backup – Optimized
An optimized script from SQL expert TheSQLGuru that shows the last backup time for all databases, covering the last full, differential and log backup.
Learning SQL Wait Stats: The Complete Series Guide
Learning SQL Wait Stats is the fastest way I know to find out why a SQL Server is slow. This guide lists every post in my wait stats series, told as one story about an all-night diner, and answers the questions readers ask before they start.
Counting Current Connections by Login, Host and Application
Try counting current connections by login, host, application and database, then inspect sleeping transactions and save a baseline.