ITMA.
Firefox 55.0.2 has reduced my W7Starter-IntelAtom-Netbook, to a quivering wreck.
Firefox 55.0.2 is 'up, not responding, up, not responding', in a silliness loop of the prime magnitude. WHAT TO DO ?
1. Localise the problem. Didn't take long. 'ADBLOCK PLUS' browser extension.
2. Gave the extension a darn good thrashing. No good. 'REMOVED'.
I like my browser-extension-toys; but, where to go next ? 'ADGUARD - AdBlocker' !
Loaded 'ADGUARD - AdBlocker' browser-extension, setup the options.
Firefox 55.0.2 LIVES !
So, what's the browser setup ?
Firefox 55.0.2 : Norton ConnectSafe DNS, Policy 1 : Norton ToolBar : Privacy Badger : ADGUARD - AdBlocker.
A very slow machine, has a new lease of life. Hope it makes the W7 - 2020 cut ?
"It's That Man Again."
The SinecolSirphor. AK. 
all other Adguard AdBlocker switches Off.