Power Query very long loading time

Hi guys,

i have a SQL query i added in Power Query. Now i am adding additional custom columns to transfor some columns coming from the query. But often times when i create additional columns Power Query takes long time to apply changes. These are also often simple transformation e.g. transform a date to only the year of the date. 

Now my question is: Is Power Query querying the database everytime i create a custom column that refers to a column from the query? In general when does Power Query query the databases? 

I assume that because in the lower right corner i see this notice: "Waiting for host:" and then the name of the database. So it looks like Power Query always queries the database. 

This is super annoying. How can i work around this?

Thx guys