1khz fps. One check per milisecond seems good enough. At 400kbps, one transaction may last less than a milisecond. If the sensor is the only slave on the bus, you could run i2c with dma transaction under interrupt, and trigger this i2c transaction by timer 1msec event. This being very specific and free the main code from dealing with low level management or need to use rtos and share the resource of i2c.
Various schemes exist and it depends on the overall picture.
