Q 1 - More than one antivirus app - This computer has multiple antivirus apps installed.
Q 2- AntivirusforMac.app, Bitdefender, and Trusteer
A 1 and A 2 - There are no known Windows-like Viruses in the wild that self replicate and affect macOS, because of the underling UNIX Foundation and Permission Limitation.
The Only thing this Antivirus software is protecting is the Bank Account of the Developers and for zero return to the User aside from the problems this software creates.
The The Built in Security is all that is required to protect the computer.
Any Third Party Applications that will interfere with the normal operation of the OS, alter, modify, remove or delete or attempt to do so is an invitation for disaster and comprising the Operating System
Any of the below should be removed as per Developers Instructions
This will include BitDefender , and AntiVirus for Mac plus Trusteer
Q 3 - System modifications - There are a large number of system modifications running in the background.
A - 3 Any time the computer is running so many Modifications to the OS, there are sometimes unintended consequences to the performance and behaviour of the Computer. This may be what this computer is experiencing