This paper proposes an approach to improving the performance of Thakore's algorithm with the speculative execution technique and dynamic task scheduling. Recently, object-oriented databases are being used in many applications, and are becoming larger and more complex. As a result, their response time is becoming longer. In order to reduce the response time, many parallel query processing approaches are proposed. The algorithm presented by Thakore et al. in 1995 is one of the representatives of such parallel approaches, but has a problem on load balancing. In order to reduce the problem, we modify this algorithm in two points: (i) introduce the speculative execution technique, and (ii) adopt dynamic task scheduling in assignment between a class and a processing node. These two modifications lead to a performance improvement of the original algorithm. Its effectiveness is shown with some evaluations.