Firebase Cloud Functions can sometimes take a bit to get going, especially if you've got a lot of dependencies. To speed things up, try to keep dependencies to a minimum—only include what you really need. Also, consider using global variables to store initialized instances so you can reuse them later.

Instead of running similar operations one by one, use batch and aggregate methods. This can cut down on the number of function calls, saving you time and money. For example, if you need to update multiple documents in Firestore, go with batch.update() rather than calling document.update() multiple times.

The cost of running Firebase Cloud Functions depends partly on how much memory you allocate and how long the function runs. Pick a memory size that makes sense for your function. More memory means higher costs. Also, try to reduce the execution time to save money. Setting a reasonable timeout period can help keep costs down.

Adding retries for your functions can ensure they complete important tasks without you having to step in. This is especially useful for functions that talk to third-party services or APIs that might be temporarily down. But be careful—retries can add up in cost if not managed well. Set a max retry limit to keep things under control.

Sometimes, Firebase Cloud Functions can get triggered more than once, like when Google Cloud Pub/Sub retries unacknowledged events or Firestore reacts to the same event multiple times. To avoid these unnecessary calls, make your Cloud Functions idempotent.

Make sure your Cloud Functions only trigger when they really need to. Fine-tune your Firebase triggers to activate functions only when necessary. Use specific database paths, cut down on background triggers, or use callable functions that run only when the client app explicitly calls them.

Shift heavy computation tasks to the client side whenever possible. Firebase Cloud Functions can get pricey for data and computation-heavy tasks. Offloading these tasks to the client can save you a lot of money.

Saving costs also means making the most of free resources. Firebase offers a free Spark Plan with a fair usage limit for Cloud Functions. Be sure to use these free executions before moving to a paid plan.