I2C protocol delay problem

Hi all,
I use the <Wire.h> library and want to communicate with INA226 power management chip.
I modified the Wire.h library to increase I2C speed up to 400K hz.
Then script the code. (function: repeatedly read 0x01 register content)
Using logic analyzer capture the protocol, there was about 20-25us delay between old and new generation. (as attached figure)
Why does there are a delay occurs?

My hardware: arduino Uno R3

INA226_0907.ino (387 Bytes)