In my opinion, worrying about performance and security is a bit pointless when you’re booting from a HDD into an operating system that hasn’t had a security update in over 4.5 years.
Assuming your dad doesn’t know or care too much about computers, I would just install ChromeOS Flex on the thing, maybe install an SSD, and call it a day. No need to worry about installing viruses if the computer doesn’t support installing software to begin with.
I used Norton until recently when I gave up on having to set up a new email account for it every year to avoid the ridiculous £80 renewal cost, and it was only when I looked into Microsoft security essentials again that I found out that Defender was already there just waiting to be used. My machine has been transformed with Firefox no longer crashing every day. It turns out that Norton was the only virus that ever got into my machine and I wish I’d got rid of it sooner. The only good thing about using it was that it never found any other virus, thereby showing me that I didn’t need it.
Reminds me of this blog post from a former Firefox developer, stating very clearly:
antivirus software vendors are terrible; don’t buy antivirus software, and uninstall it if you already have it (except, on Windows, for Microsoft’s)
So I’m not surprised that Norton injects their own code into Firefox and causes it to crash.
@HuyRemy is that picture from Github where you are photographed in Japan?
I ask because I have the impression that the steering wheels on cars are on the right and your country is LHD
@Oxy
Exactly, it’s me, that’s picture @ Fukushima - Japan. But Japan is not my country, I’m from Vietnam. 
Yes, it’s true. But you never know @ my country have a hosting provider (Paid Hosting Provider) who have just defaced all his clients with his malware ads textlink. This is his victim (Link_Removed_By_Mod) then…you are the chosen one.
No, I’m not glow in the dark. My name’s Quang Huy - Nguyen Quang Huy, in Viet Nam and China, Quang Huy is meaning is Sun’s Light, I’m glow from the beginning. 
In the trurt, I’m from Viet Nam, last time I come Japan after that have a nuclear disaster in a factory at Fukushima, I have some mission must be done there, that’s trip only fews week. You know, I’m not familiar with Japan.
About Ukraine War, I’m watching you, I have some friends still living in your country if you want I can share to you the Russian Military Trops Maps (Intelligence)
Now, @ Vietnam is Mid-Autumn Festival. This is moon cake, Vietnamese use moon cake in Mid-Autumn Festival, and…yes Zelensky very famous name, the best trademark, you see. Cheer !
@HuyRemy my apologies for thinking you were from Vietnam but actually, you are from Japan !
@lovebug Thanks for the notification and correction - I’m stupid for not remembering to look at BIO 
I’m still not drunk, you know vodka never make me drunk…but may be the computer is drunken. Let me see, you are alien and you come from Mars, right ?
I also want to come to Japan, but never came to know this place and since you are from Japan, I wonder you know the place as well, so you can also let me explore some things there since I don’t know how is culture there.
Anyway, @HuyRemy, have you ever traveled to Vietnam?
Find a wife?
+ 
= 
Well…the first, Japan is a beautiful country, you can have steam bath onsen everywhere, ,certainly steam bath with monkey, the true monkey, let imaging, you take a bath and monkey come and take a bath with you, the real monkey…it’s cool ? And food certainly Japanese is sushi, that’s the fish It but not a freshwater fish. In Japan people do not eat freshwater fish. And very many interesting there. Come, you should visit Japan to see, may be you will like that country.
And…the 2nd, I was born in Việt Nam, I’m grow up in Việt Nam, I’m living in Việt Nam, yes sure I’m Vietnamese. I’m traveled to Vietnam in a nearly a half of century before.
No dear, that’s the top secret mission. Man only, like military’s mission. nuclear mission, you know ¿
I’m just as confused as everyone else here 
Are you from:
a) from Japan
or
b) from Japan
???
be careful when sharing pictures - someone will take your fingerprint !
