Is RealTime Antispyware Protection needed with FireFox?

Immediate System Recovery softwares, like FDISR, RollbackRx, PowerShadow, ... allow malware to install/execute themselves.
ISR-softwares are NOT security softwares, they only REMOVE CHANGES, including malware during the next reboot.
If malware is installed and executed between two reboots or two scans of a scanner, it's too late.
So if you have only ISR as protection, your security is worthless, you only have a very good and fast cleaning method during reboot, that's all.

ISR doesn't remove only the bad changes, but also the good changes like security software and non-security software updatings.
If you like to keep those good changes, you have to disable the ISR-protection to allow these updatings.
That's a problem and you have to depend on your security softwares, when the ISR-protection is disabled.
Also the timing of software updatings is important, the safest way IMO is to do this right after reboot, when your computer is still clean.

Most softwares update themselves automatically at random during the day, which is also a problem, you can't accept them because your ISR-protection is ON and if you want to accept them, you have to turn OFF ISR-protection.
This means that you have to disable all automatic software updatings and do them manually right after reboot when your computer is still clean.