Performance

I have 50 Queries, whoose do same thing at first steps

Queries editor
SOURCE = Sybase.Database("165.165.156.15:2638", "EUR")
Navigation = Source{[Schema="DBA",Item="db1"]}[Data]

So i have long to wait on each refresh.

Is there are the way to reduce refreshing time.

Do that inncrease the performance, if:

1. I will have only one SOURCE = Sybase.Database("165.165.156.15:2638", "EUR"), and do all others Navigation with Reference on this Source?
2. I limit rows by date for example only dates starting from 01/01/2017? but in sybase it impossible to reproduce? it is possible to do this dinamically?
3. I disable background queries running, but this is not working for me, as i didnt see any performance improvment by this.
4. I delete not using collumns, but how to determine which columns is not used in my model?

5. I have lot of same slicers (20 slicers) on each page (20 pages), so just slicers loading abount 30 sec., how reduce slicers loading time?