Using only Rx pin to receive data from HC 05 and attiny85 (Arduino IDE)
I suggest you get rid of SoftwareSerial and use instead this Simple
ATtiny USI UART. This is a driver
for a receive-only UART that uses the USI port of the ATtiny85. It is
superior to a software-only UART as it makes good use of the hardware,
leaving more time for the CPU to do more useful things (or sleep and
save battery). Also, unlike SoftwareSerial, it does not need to block
interrupts for long periods, which is a good thing.