Rapid growth of IoT networks as well as increasing number of wireless devices working in the frequency band of 2.4 GHz and 5 GHz, causes a saturation problem in wireless networks due to the high number of simultaneously operating devices. To solve this problem, IEEE 802.11 working group has released the IEEE 802.11 ah (Ha-Low) standard working under the sub 1 GHz. IEEE 802.11ah implements the feature of Restricted Access Window (RAW) mechanism, which splits stations into groups, therefore reducing packet collisions. In present work we evaluate an impact of the RAW mechanism configuration with improved page slice adaptation on the performance characteristics of 802.11ah standard such as channel capacity, transmission data rate, packet loss, and energy consumption using numerical analysis and computer modelling with ns-3.