EC2 -SQL Server Slowness

@riku - No we don't have any difference. the settings are identical.

Hello.

What is the CPU usage rate and memory usage rate of EC2?
I think the database may use a large amount of memory depending on the processing.
Is it possible that that is slowing down the queries?

I think the following blog will be helpful for tuning.
https://www.sqlshack.com/troubleshooting-the-cxpacket-wait-type-in-sql-server/

Also, what type of EBS are you using?
If you are using gp2, try using a volume type with high iops performance such as gp3 or io2 to see if the query speed improves.
https://docs.aws.amazon.com/ebs/latest/userguide/general-purpose.html
https://docs.aws.amazon.com/ebs/latest/userguide/provisioned-iops.html

Hi Thanks for your response. CPU is below 20% and Memory i have allocated to SQL Server 100 GB. We run on GP3 4k IOPS and 1k Throughput. Im testing the server with one query at a time. The query completes faster in the onprem version but its slow in EC2.