When a task is committed in PSO, it is taking too long (sometime upto 15-20 min) to reflect in PSO

When a task is committed in PSO, it is taking too long (sometime upto 15-20 min) to reflect in PSO.
This has been a issue since day 1 of FSM and PSO implementation in TDC. Normally it takes around 3-4 min to reflect in PSO but after 2,3 days it is getting very slow (it is taking 15-20 min) that users are unable to work on and completely stand still condition coming for them and at the same time we are experiencing slowness in FSM also, then if we are restarting the gateway services and after that it is becoming normal again (it is taking 3-4 min) and FSM also becoming normal. So the story is that in general it is normal slow (3-4 min) but after 2, 3 days it is becoming abnormally slow (15-20 min). There is something happening in PSO services, which is giving this slowness and after the restart it is becoming normal again. We have priority 2 Incident running for this issue and as a workaround we have planned to restart the gateway service in every alternate day to improve the performance. Please help on this urgently and come up with some solution. Why the resatrt is being required to improve the performance