Context : Be stars are physically complex systems that continue to challenge theory to understand their rapid rotation , complex variability and decretion disks . \gamma Cassiopeiae ( \gamma Cas ) is one such star but is even more curious because of its unexplained hard thermal X-ray emission . Aims : We aim to examine the optical variability of \gamma Cas \xspace and thereby to shed more light on its puzzling behaviour . Methods : Three hundred twenty-one archival H \alpha spectra from 2006 to 2017 are analysed to search for frequencies corresponding to the 203.5 day orbit of the companion . Space photometry from the SMEI satellite from 2003 to 2011 and the BRITE-Constellation of nano-satellites between 2015 and 2019 is investigated in the period range from a couple of hours to a few days . Results : The orbital period of the companion of 203.5 days is confirmed with independent measurements from the structure of the H \alpha line emission . A strong blue/red asymmetry in the amplitude distribution across the H \alpha emission line could hint at a spiral structure in the decretion disk . With the space photometry , the known frequency of 0.82 d ^ { -1 } is confirmed in data from the early 2000s . A higher frequency of 2.48 d ^ { -1 } is present in the data from 2015 to 2019 and possibly also in the early 2000s . A third frequency at 1.25 d ^ { -1 } is proposed to exist in both SMEI and BRITE data . The only explanation covering all three rapid variations seems to be nonradial pulsation . The two higher frequencies are incompatible with rotation . Conclusions :