Hello,
Yep, you can either type in the SQL query by hand or use tab 'Analysis' and drag and drop what you need (into attributes - Labels and measures - Values) . Check the genereated SQL using the 'Show Log' button at the top-right side of the Data preview panel.
No Plv so far. However, before attaching anything else, try to reduce as much as possible the amount of columns and check if the performance is better or not. If you still need some help, then go ahead compress your plv file and attach it here.
BRs,
Lucas de Oliveira