niroj Thank you for the screenshots. You mentioned,:
There are many bones which are duplicated in order to animate gold and money raining etc
but normally 105 bones should be no problem at all. From the information of the Metrics view, the complexity of your skeleton seems to be roughly twice that of Spineboy, and unless that skeleton is going to be displayed on the screen in great numbers, there should be not much necessity to optimize.
You might want to tell your clients to post a question about the problem on this forum, since the information we can find on the Spine editor does not tell us much about the cause.