SSAS extremely slow after RLS implementation

Question

I have an SSAS that is consumed by some users using Powerbi and excel.

Its being used and works perfectly; but now, I have introduced some RLS security and for people accessing with limited permissions, it is awfully slow...

How can I troubleshoot this?

I have 3 roles:

Role1 (Everyone has access).

RLS

Employee Current table:

 =[NT Username] = USERNAME()

Projects table:

=[Key_Project] IN
SELECTCOLUMNS(
    FILTER(
        'Engagement Role'
        ,'Engagement Role'[UserName] = USERNAME()
        )
    ,"Key_project"
    ,'Engagement Role'[Key_project])

Role2 (Everyone has access too):

Employee Current table:

=[TeamLeadEmployeeID] IN
SELECTCOLUMNS(
	FILTER(
		'Employee Current'
		,'Employee Current'[NT UserName] = USERNAME()
	)
	,"RLS_Ids"
	,[Employee Number])

Projects table:

= VAR MyEmployeeNumber=
SELECTCOLUMNS(
FILTER(
'Employee Current'
,'Employee Current'[NT Username]=USERNAME()
)
,"EmployeeNumber"
,'Employee Current'[Employee Number]
)


VAR My_Employees =
SELECTCOLUMNS(
    FILTER(
'Employee Current'
,'Employee Current'[TeamLeadEmployeeID] = MyEmployeeNumber
) ,"EmployeeNumber"
    ,'Employee Current'[Employee Number]
)


    

RETURN
[Key_project] IN
SELECTCOLUMNS(
    FILTER(
        'Engagement Role'
        ,'Engagement Role'[Employee Number] IN My_Employees
    )
    ,"Key_project"
    ,'Engagement Role'[Key_project]
)

The 3rd role that doesnt matter much, because it has no fitlers, its to provide Read ALL.