Autocomplete should help someone finish a search, not spend the request budget on every key press. A short pause before requesting suggestions can reduce noise, but a delay alone is not a complete design.
Start by deciding when a query is meaningful enough to send. A single character may produce a broad list that offers little help. Choose a minimum input length based on your supported languages and test it with real examples rather than treating one number as universal.
Keep the suggestion request small
Use the documented autocomplete route where it fits. Ask only for the allowed number of suggestions your menu can show. Cancel an earlier request when the input changes, and ignore any response that no longer matches the current text.
Cache a small number of recent suggestion results for the current session. Include the query and any language or type option in the cache key. Avoid sharing personalized search text between users through a public cache.
Distinguish a highlighted suggestion from a submitted search. Arrow keys can move through suggestions; Enter should perform the action the interface clearly indicates. The full search button should remain available when none of the suggestions fit.
Check slow and expensive cases
Type quickly, delete the input, paste a long title, and use a non-Latin keyboard that composes characters before committing them. Do not send incomplete composition text as if it were a finished phrase.
Watch how many requests these actions create. Add a clear fallback when suggestions fail: the listener should still be able to submit a normal search. Autocomplete is an aid to the task, so its failure should not become a gate in front of discovery.