This question already has an answer here:
I have an SQL Server instance running on AWS RDS that is performing badly. A query that usually takes milliseconds to run, is taking minutes, causing my application to time out. This particular query SELECTs from a table which has 50000+ rows, but it only returns 100 rows (with a SKIP/TAKE parameter). I managed to replicate the problem on SQL Server Management Studio, so it's not an application problem.
When I reboot the instance, the problem is gone. But it comes back randomly within a few days. What could it be? And how can I troubleshoot it?
Engine version: 14.00.3049.1.v1 (SQL Server 2017 - Express)
Instance class: db.t2.micro
RAM: 1 GB