Fast Reterival

We have some reports which have more than 200,000 rows of data. The query for the reports run in 4 min in Teradata SQL assistant but when we run the report in 3.1 webi, somehow it shows the output within 10 min. Although I would expect it to show output in at least 6 min given that there are no report side calculations or special formatting involved?

1) Why does it take such a long time in 3.1?

2) When we run the same report in 4.0, it doesn't show any output. How do we make it to work at least like 3.1? Should we modify the fetch size or something?

2) sometimes 4.0 shows data and sometimes it doesn't for the same query and same data. What could be the issues? How do we fix it?

Thank You