I2C Slave problem from >5.085

[Ttelmah]

Generally also, if a device sleeps when not working, the total power
consumption, will often remain pretty constant over a wide range of
speeds. There is an upper speed where the core starts to actually run
inefficiently, and a low speed where the sheer time the other devices
have to be powered becomes the major power cost. Keep your
operating speed between these limits and you have the lowest power
In the case of low power PIC's the speed where the core starts to run
inefficiently may be well above what you expect.
In the case discussed here increasing the value of the I2C pullups
will reduce the power needed when driving the I2C. Keep the I2C clock
rate low, and the losses into the bus capacitance will be minimised.

[monsun]

Thank you guys for help with debugging, this is AFE pcb for sensors which in standard works on battery but have also software on PC to make some service adjustments. Working clock have to be pretty fast because it is making 100 readings in a second period which are averaged for bigger precission. It is also used in IOT application where it is put in sleep and wakes up for 2 seconds to make readings.