If you need a fast, reliable way to write data, consider using flash-chips. This video shows how to use a database driver to store fields of data in record format--a database.

The library being promoted can store up to 255 data fields and save data at the rate of 50 bytes / millisecond. You can write multiple fields with a single call. Data can easily be retrieved and saved to an SD card.

This library is intended for saving data from a datalogger where know fields are to be stored. It's not for storing image/audio, or data with unknow lengths.

Download the library at:
https://github.com/KrisKasprzak/TeensyDB

Tested with
- Teensy 3.2
- Teensy 4.0

Flash Chips
- Microchip SST25F040C (https://ww1.microchip.com/downloads/e...)
- Winbond 25Q64JVSIQ (https://www.winbond.com/resource-file...)