@Kr1tycal said:
Rate Limit
Hi,
I've been using your API for some time for a hobby project and recently I noticed that my request times for getting things such as the cast of a movie, or the movies and actor has played in has slowed down drastically.
It now takes around 0.6 seconds per request.

You can check the system speed here:
https://status.themoviedb.org/
https://status.themoviedb.org/#/components/CV8aDz4Xn5ikJZrRQr_JNPHGtfSICRu-BHYPYCxe7yE-PLIQyS5PhDhNwnIo19QO

I was just wondering if this is a rate limit issue or an issue with how I am sending the requests.

As for the rate limit, see the data I have below.

API Request Limits
First we have this information in the instructions for using the TMDb API.
https://developer.themoviedb.org/docs/rate-limiting
And Travis Bell, the Administrator, has already given us this explanation.

For API Requests:

One of our CDN providers enforces some base level rate limiting to help prevent DDOS attacks.
I believe it's a maximum of:
50 requests per second and
20 connections per IP.

See here: https://www.themoviedb.org/talk/62c7c1b258361b005fd2e747?page=1#62c83b78befd91005007a0c7

For Images:

For image.tmdb.org the only thing we limit is the max number of simultaneous connections.
The limit is the same, 20.

See here:
https://www.themoviedb.org/talk/62edd3ca46aed400917de201#62ee88e7176a940086449cdf
https://www.themoviedb.org/talk/62c7c1b258361b005fd2e747?page=1#6301a107097c49007f60374a
https://www.themoviedb.org/talk/62c7c1b258361b005fd2e747

And...
Is there really no API Rate Limiting?

The original rate limiting (40 requests every 10 seconds) has indeed been been disabled since December 2019.
There are some higher overall limits that still exists to help mitigate different attacks and the like.
I believe they sit around the 50 request per second range.

See here:
https://www.themoviedb.org/talk/6442ced4d35dea02fcfb0fab#6442d4a0d35dea0455fb1a07