does INPUT_PULLUP uses power?
Only the leakage current on the input itself is constantly consumed if there is no external connection. This is usually much less than the waste caused by having the input floating.


  If a voltage between 0.8 V and 2 V is applied to the input for a prolonged period of time, this situation becomes critical and
  should not be ignored, especially with higher bit count and more dense packages [...]. For example, if an 18-bit
  transceiver has 36 I/O pins floating at the threshold, the current from VCC can be as high as 150 mA to 200 mA.