It ispossible, although tedious, to revert system apps (and user apps as well) back to versions that would make these devices perform as you remember.
The problem, besides the hours of time, is that those versions of apps may very well no longer function online with the sites they link to.
To be sure, it is highly likely that the devices really could be useable online, most likely not for gaming but for general online stuff.
Also, keep in mind that these things are ancient by today's standards, and technology with such devices moves ahead faster and faster.
To be sure, you yourself said that you have not used it in quite some time.
The speed that you remember is not going to be fast by today's standards.
I have every smartphone that has ever been mine- even dumb phones going back to 2001 (which was a 1997 version when I got it!)
When I do fire any of the old ones up, I am amazed at how slow they seem now, although I thought they were great when I was using them.
My ol'lady is still using a 7.1.1 that I have two of.
These things were great when we got them.
They did require routine clearing out, because the memory capacity was small.
So when her phone starts acting up, I have to do this maintenence on it.
Basically, I move her pics and videos to the SD card, delete any duplicates, update important apps, and clear the caches of all apps.
Then I do a restart.
This is what I do on a weekly basis with my devices (I tend to run two.)
With my current device, this can all be done in minutes.
With my slightly older device that I actually use as a phone, it takes a bit longer for each function.
Not a ton, but it is obvious.
I thought that device was fast (and it WAS the fastest device I ever had) until about 7 or 8 months later and I get this other device.
Now, when I go to do the service on my ol'lady's phone, I swear it is like dragging an anchor.
It took me hours, no kidding, because she had it so full and it is just that slow.
I always had a complaint with how long those 7.1.1 devices we have took to install updates or to restart them.
It takes about 2-3 minutes just to restart, whereas my phone (with double the memory, an octo core processor (the others are quad core) the same RAM but a better chipset) does it in about one minute flat.
Up until my latest devices, I just assumed that restarting took a long time.
Now it is like nothing.
Her battery is going bad, and although I can get her another one, I have already got her a new phone.
This was months ago, but she never activated it- now the carrier probably won't anyway.
Anyway, the point is that the devices we liked years ago in their prime are nothing compared to the devices of today.
These things have a typical useful lifespan of 2-4 years, but they will be outclassed long before then.