Yes, it's perfectly normal.
The way you are building the viz (dimensions on rows and columns) defines your aggregation (i.e. sales by region) and this goes into GROUP BY clauses. IF/THEN calculation is usually turned into CASE, especially if it has branching (nested IF/ELSE or ELSEIF).
Yeah you can get rid of those but then you would have to not use filters and uncheck "Aggregate Measures" under Analysis menu. Not sure if you would be able to get any useful information our of such viz though :/
Did your admin happen to suggest what would be the equivalent query that would produce same results but would be faster?
What I is that your database can't really handle Tableau load which happens. Going forward this should be a collaboration between you and DBA to potentially make necessary changes in database (indexes, normalization etc). On your side you could avoid complex string operations (CONTAINS(), wildcard search etc). Teamwork!