getAllTmGroups is taking too much time to respond

We have recently noticed long delays in getting the translation memory groups. This is how we do it :

var tmManager = this._wsContext.getTmManager();
var results = tmManager.getAllTmGroups()

The call to getAllTmGroups() takes between 30 and 38 seconds, although there's only 91 groups.

In comparison, getting the translation memories is much faster :

var results = tmManager.getAllTms(false);

This only takes less than 1 second to return 114 records.

Is there a reason getAllTmGroups() is taking so much time ? Maybe you could indicate which Oracle tables are involved in the query so our DBA could investigate if it requires some fine-tuning ?

Thank you.