Sophos Central Firewall Manager unusable? - performance issues

I don't know if I am doing something wrong, but the CFM is absolutely unusable for me.

I tried different browsers, everytime it is ending up the same...
We have only 12 managed customer devices in our Sophos Partner CFM and it runs slow as hell. When I click "Managed Devices" it takes up to 2 minutes until some data is displayed... if it is displayed at all. After clicking around a bit the complete CFM session seems to crash (loading forever) and reload of the site is the only thing to do.

That is the reason I cannot use any central configuration things or even have a look on the devices alerts, firmware revisions or anything else. In the actual state CFM is absolutely unuseful for me and I have to look into every device via local WebAdmin.

Anyone else having problems like this? It is no actual "COVID19-slowdown-issue", it was never usable for me since we deployed our first XG.
I am aware that a "cloud management console" cannot have the speed of a local SUM, the local SFM we tried at first had a very bad performance, too.