Hi @onsche, increasing the priority of the Game itself (Rather than the Tobii Service) may help to alleviate frame drops.. did you try this already?
Regarding different performance across titles, this can relate to certain components shared between Tobii and the Game manufacturers that we try to maintain constantly.
In the past, software issues were identified with head tracking remaining enabled despite being disabled within the game settings. The resolution was for the game developer to update the Tobii component of the game, which unfortunately is not something we can actively control. It may be worth therefore posting on the game developers own forum about this issue to see if they can patch the problem for a future update.
As you mentioned, your CPU is rather old (2012) so is not ideally positioned to handle the latest titles in conjunction with Tobii Tracking. Did you already upgrade the hardware?
Thanks for your patience whilst we try to investigate any further options. Best Wishes.