Consider some Best Practices for Solarwinds DB Maintenance
Ask yourself the foll questions
1. Is my DB Size causing me performance issues
2. What are my polling frequencies for devices
3. What is my Poll stats collection frequency
4. What is my data retention policy
The best practices guidelines in the link above should help.
Also seek help from a DBA to address Indexing issues, fragmentation, log etc
when the Orion DB starts to grow what table is growing? Do you have syslogs and traps coming in? also, what is your recovery model on the DB full or simple?