High memory consumption by Firefox in undertow subsystem

Firefox consumes too much memory when user repeatedly enters this subsystem. Firefox starts eating memory after at least fifteen to twenty reloads and reenters, so this issue will appear in minor count of use cases.

Measured values below are from standalone run, undertow tests run from ~08:00 to ~08:50.

Left axis of graph describes use of CPU in percents, right axis describes use of memory in kilobytes, x axis describes time. Firefox was run by Selenium. Firefox instances were tracked using output of ps command which run as daemon using bash script. Log file is in this format: [TIME] PID MEM %CPU.