less no of database connections and Multithreading

We have a Multithreaded application that is 10 year old. It worked fine for all those years suddenly it was too slow. The reason was while threads are created database connections are fully used and threads had wait on each other for the resource. The database configurations are defined in application for data source. It had max connections of 3 and min of 1. we changed the maximum connections to 30. it worked like a charm.