[Sophos UTM 9.000] High memory/swap usage

Hello,

See the screenshot below for a monthly view of our Sophos UTM memory usage.
I think that the swap and memory usage is verry high. After a reboot it is normal for a few days but grows up fast.
Is this a problem? We have 3.3gb memory.
CPU is normal around 15%

We have the following services enabled:
- Firewall
- Intrusion Prevention
- Web filtering
- Network visib.
- FTP & SMTP proxy
- Antivirus, antispam & antispyware