1. How many coins have you enabled in CoinPayments? Does the problem persist if you only enable e.g. one or two coins? Normally the adapter should be able to handle many coins, but if your server’s connection to CoinPayments is slow, this could be an issue.
2. If the get_coins_info call takes too long to complete, this is likely not an issue with the plugin, but is specific to your setup. There is only one fast way to debug this: Deactivate all your plugins one-by-one until you see a change to the response time on the frontend. If you can pinpoint the issue as arising from a specific plugin, I can investigate further why this is so and what can be done about it.
3. Please open up the network tab in your browser’s console (F12) and refresh the wallet page. How long, in seconds, does it take for the XHR requests to complete? The [wallets_balance] shortcode requires the get_coins_info call to return. How long does this take? Let me know please.
Having said this: If you are using too many shortcodes in one page, the frontend will be slow, unfortunately. This will be resolved in the upcoming version 6.0.0 of the plugin, because it requires architectural changes.
Please try to provide answers to all three questions so I can help you. Looking forward to your reply.
P.S. I have moved your post from the CoinPayments adatpter forum since it is likely a more general issue not related to CoinPayments.