As the hits per second increases....
1. If the application is good enough to high user load, we dont see any changes in teh response times with respect to hits per sec
2. If the application is not good enough & with performance bottlenecks then response times gradually increase with increase in hits per sec.
3. Finally if there is any network delay which occurs intemittently in some instances will increase the response times of all the transaction at that moment & hence due to which hits per sec & throughput decreases.