Merging queries has performance issues

 I am working on pibx file. The file takes data from 3 to 4 different tables of SQL database. The file also gets data from 3 to 4 CSV files. The size of csv files varies from a few hundred kilobytes to 5 MB. I used merge queries and attach desired columns from a couple of csv files into fact tables. I noticed that the performance of pibx file (slow down) after using merge queries. I worked on the optimize the performance of pibx file and reduced the size of the pibx file reduced from 35 MB to 16 MB.

However, I am still facing a performance issue. When I tried to refresh the data, it never refreshed the data. For some tables, it says that evaluating and for other tables it says waiting for other queries. I waited for a couple of hours but the same status was showing and it did not progress further

sample file can be download from here

Any help would be really appreciated.