you could add a loader to the page to distract the user
most web apps do this - even simple apps like gmail
just create a float that covers the whole page with a loader gif on it and use “when page is loaded” to hide it
if you’re referencing data in a repeating group then you could also use “when repeating group loading is no” to hide it
possibly the data you’re trying to access in the dropdown is quite heavy which is why it takes seconds to load it