Hi owais.ko,
Is the problem general in nature? Or does it happen when running specific reports? How many users are concurrently using the system when you notice sluggishness?
Have you checked the memory usage and allocation of the web service in STM? Slow web console response is often caused by the Web Service running low on memory. You can see how to adjust the memory used by individual STM services in Chapter 5 of the STM Admin Guide.
