SQLite.Net-PCL terrible performance (InsertOrReplace)

foreach (var tour in Tours)
            {
                await DbInstance.InsertOrReplaceAsync(tour.Guide);
                await DbInstance.InsertOrReplaceAsync(tour.Client);
            }

This block takes 6 seconds to execute !?

I have only 10 tours in Tours list and database schema is really simple. What is the problem here?