This library defines only one function: getDS1307timeStamp().
getDS1307timeStamp() gets from the RTC a timestamp string like "YYYY-MM-DD hh:mm:ss" for dataloggin pourposes.
The function is fast, it takes only 1.132 ms (1.128 - 1.142). Using Process to get Linux time (using an Arduino Yùn) take more than 1 sec (see PollingTest example, here: https://github.com/msillano/Arduino-library-Polling/tree/master/examples/PollingTest).
If one of I2Ctunnel or I2CtunnelW library are used, this library uses low level I2Ctunnel read. Else it uses local I2C read function whith Wire lib (see USE_I2C and USE_I2CW).