How to run the internal RTC on the ESP32 without internet access?

I built a 4-temperature logger which creates a CSV file on an internal partition in flash for downloading via the web, the chip works in AP mode and has a small configuration via the web. It is also possible to view the graph via www and google script, I also made graphs via Ajax. Unfortunately the graph only works on the phone because the script loads from the internet, which is about 100KB. When I upload it to the internal memory and read it
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Unfortunately I achieve about 2KB/s. Which makes the file take a minute to download. Maybe someone has some other idea?

Let's move on to the 100th issue.
I need to use an internal RTC for which I found no description in the arduino. I know it is not very accurate. I have a 32.768kHz quartz connected.
I don't have internet access, the time will be set via the web. It will be added to a CSV file to show indicatively when the measurement was.

I am writing in Arduino, ESP-IDE I have seen some elaborate example.
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But this library is standard in the arduino libraries for esp32? This is what I'm referring to.

Thanks a lot I saw something about this, but now with this IDF you have brightened me up, the RTC clock works. And could you advise something else with file uploads?

Hmm, but will it do that much? I thought the problem was more on the client.write side and sending a single character.

But after all, that's all the code in the first post. While checks if the file has finished, file.read read reads a character from the file and increments a pointer to the file and write writes a pointer to the client connected via http on clnt. This while with a 100KB file takes 50s.