Multiple users authorization for one resource

Getting advice
1

I have protected server resources with authorization services and everything works fine. But now I have a requirement to evaluate permissions for N users at once. I managed to implement it using following algorithm:

  1. Impersonate required user to get access token for him
  2. Request RPT for given resource with token acquired previously
  3. Send introspect request in order to receive permissions list

We loop over all users and repeat this steps for each of them which results in N*3 request to keyckloak. Does there any way to optimise this?