How to determine Frequency response in BJT
In the datasheets of the BJT transistors, common emitter cutoff frequency, \$f_T\$ is usually given. At this frequency the magnitude of the common emitter current gain equals to one, \$\beta_{f_T} = 1\$. As a rule of thumb for BJT's, we can say that a BJT transistor as an amplifier is usable up to the frequency \$f_u = f_T/10\$. 

The distortion depends not only on the characteristic of the transistor (such as \$f_T\$), but also on the circuit the transistor is biased to. For example, the capacitors being used to block DC currents reduce the upper (and also lower) usable frequency of the transistor.