In order for the ZoneMinder montage to display correctly under Firefox, the following settings must be made:
Navigate to about:config
browser.cache.check_doc_frequency 3 -> 1
browser.cache.disk.enable True -> False
browser.cache.memory.enable -> False
network.http.use-cache -> False
network.http.max-connections-per-server -> 100
network.http.max-persistent-connections-per-proxy -> 100
network.http.max-persistent-connections-per-server -> 100