Multiple Many 2 Many relationships and optimizing them

I have the below design in one of cube:

  CONNECTIONS (FACT) -> LOGIN (DIM 1) ->  LOGIN_PROID_MAP (BRIDGE 1)<- PROID (DIM 2) ->  LOGIN_PROID_OWNER (BRIDGE 2) <- OWNER (DIM 3) 

I have created 2 bridge tables so use them both as fact and dim : LOGIN_PROID_MAP and LOGIN_PROID_OWNER 

the problem is because there are 2 m2m relationships the performance it very slow when i select owner details for connections,also there are 4 million logins that adds to perf issues. 

Any suggestions to improve performance please?