The latency for Plaid's real-time balance endpoints — /accounts/balance/get, and /signal/evaluate when called with a ruleset that includes a balance rule — is higher than other endpoints because they retrieve fresh data from the financial institution each time they are called.
Unlike other Plaid products that provide balance information as part of the accounts object and update on a regular cadence, these endpoints can provide real-time balance information. This means that each time /accounts/balance/get is called (or /signal/evaluate is called with a balance-rule ruleset), Plaid communicates with the financial institution to get the most current balance information. This process takes more time, hence the higher latency.
Due to this higher latency, we recommend running real-time balance calls as a backend process rather than calling the endpoint while your end user is active on your app. That way, users can continue on your app without long waiting times.