A question about Vacuum analyze

Hello,

We have a daily cronjob and in the cronjob we do:
1. truncate one table A
2. insert into table A
3. do comparision table A and table B and update table B accordingly

The doc says "VACUUM ANALYZE command for the affected table. This will
update the system catalogs with the results of all recent changes, and
allow the PostgreSQL query planner to make better choices in planning
queries".
So, I believe after insertion at step 2, comparision will be speed up if
we do a "vacuum analyze" right?

In another way, whenever we "delete/truncate and then insert" data into
a table, it is better to "vacuum anaylze"?

Thanks a lot!
Emi