Hi @burak ,
SharePoint Online uses throttling to maintain optimal performance and reliability of the SharePoint Online service. Throttling limits the number of API calls or operations within a time window to prevent overuse of resources. So no matter you change the graph api to rest api or CSOM, you will be limited too. Even graph api performs better with large data than rest api and csom. You can refer to the document to handle the throttled limit.
https://learn.microsoft.com/en-us/sharepoint/dev/general-development/how-to-avoid-getting-throttled-or-blocked-in-sharepoint-online#how-to-handle-throttling
If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.