[Fixed]-Django render is very slow

I parsed the image at each rendering. It was bad idea.

Try to find out what takes the longest time.
You can use something like Opbeat where you can get a free account. You can see a breakdown on what takes time on different requests so you can focus on whatever is slow.

Also, is this happening only during development or also in production? Having DEBUG=True in a production setup is not only a bad idea but also it can have a big impact on performance.