Performance of multiple dropdown plugin

We created a screen using Multiple dropdown in the Repeating group. You can be searched and select items from about 600 options, where each line.

And now, the loading time (at the moment of switching the display) is very slow depending on the device specs, which is a big issue.
We expect more than 100 people to work on PCs and tablets at the same time, and we want to speed up the process even if we have to explore every possible effort.

Is there any way to improve the performance of this multiple dropdown or select2 library behavior?