Closing task window immedietly

[N-I-1990]

I have a flexi task with two actiona (Approve / Reject/ return). after the flexi task action, I start new workflow and pass the decision as parameter to the second workflow. refer to the below screenshot.

the problem is that when the user clicks on save and submit button inside the task, the task window will keep loading for around 15 seconds ... please advise how to reduce this time?