By default, the API will throttle at a maximum of 120 requests per minute, which should be more than enough for most automations.
In Snipe-IT v5.4.0, a new .env variable was introduced that will allow you to override this value. Changing (or adding) API_THROTTLE_PER_MINUTE=200 would override the 120 requests per minute to change it to 200 requests per minute, for example. If you use config caching, be sure to run php artisan config:clear after saving the changes to your .env file.
Items Returned Per API Request
As of Snipe-IT v4.7.7, API requests will return a maximum of 500 items per request by default. This is to prevent naive scripts from requesting a huge number of items, resulting in server timeouts or crashes due to memory used.
If you are hosting Snipe-IT locally, you can change the MAX_RESULTS value in your .env (or add it, if you're upgrading) to a higher number. Otherwise you should use standard pagination using the offset parameter to get your complete data set.