LIDAR speed

I tested my Lidar at 15 RPS (Hz) mirror speed.
That is corresponding to (15 Hz * (720 points/rotation)) = 10800 distance measurements per second (10.8kSPS).

At bigger scanning speed mirror vibration is higher, so I don't use it.
But I tested my Lidar at 20RPS several times. This is near 14.4kSPS.

What is the limiting factor for a scanning speed?
TDC, especially communicating with it.
I made a tests with "not_scanning_fw" - dist_measurement_do_batch_meas().
This code:
tdc_start_pulse();
tdc_read_three_registers();
Takes near 53us to execute with "SPI_BaudRatePrescaler_4" -> 18MHz SPI CLK, so measurement rate is near 19kSPS.

With "tdc_quick_check_status()" removed from tdc_read_three_registers(); measurement rate is near 22.7kSPS,
but it is problematic to understand, if measurement was correct or not without this check.

I tried to remove configure_reg1_start() from tdc_start_pulse()
and remove configure_reg1_width() and tdc_read_register_upper(OPCODE_READ_REG + 1) from tdc_read_three_registers().
With that I was able to get measurement rate near 55kSPS, BUT width measurement is not possible in this case, so walk-error correction in not possible too.