My forum (YAF v1.9.1.8) is about 25000 users, the bandwitdh is about 700GB/month, the size of database is about 2GB, the active users online is often about 150 or more, but it takes so much Ram for forum by SQL service, when I restart server and SQL service at the begining take 2GB RAM. just olny use for 4 day it takes more 4GB RAM.

Have someone know to fix this issue.

Thank for help,