How to speed up a slow API endpoint — what approaches are there?

To speed up a slow API endpoint in Go, several approaches can be applied:

1. Profiling and analysis — first, identify where the bottleneck is: CPU, memory, network, database.

2. Caching — if data doesn't change often, cache query results in memory (e.g., using sync.Map or third-party libraries) or use Redis.

3. Database query optimization — use indexes, reduce the number of queries, apply batch queries.

4. Parallelism and asynchrony — perform independent operations concurrently using goroutines.

5. Reducing transmitted data volume — use compression, return only necessary fields.

6. Using CDN and load balancers — if the API is public and under high load.

7. Code optimization — avoid unnecessary allocations, use efficient data structures.

Example of simple caching in Go:

var cache = make(map[string]string)
var mu sync.RWMutex

func getData(key string) string {
    mu.RLock()
    val, ok := cache[key]
    mu.RUnlock()
    if ok {
        return val
    }

    // Simulate a long operation
    val = slowOperation(key)

    mu.Lock()
    cache[key] = val
    mu.Unlock()

    return val
}