LRF2 becomes (sometimes) very slow

Good morning experts,

since about one month, LRF2 becomes sometimes very slow.

Starting transaction, entering warehouse number - and then you have to wait up to 2 minutes. Refresh takes about 1 second.

A little bit later, starting the transaction, entering warehouse number - you only have to wait a second. But then refreshing takes up to 2 minutes.

What can be the problem?

Thanks for your help, regards

Michael