I have two GO720 devices, both still work well enough but on one I use a large map of Western Europe and the hardware shows its limitations on roundabouts and complex junctions by not rendering fast enough. It causes me some jitters if roundabout exits are close together and against best practice I do rely on the screen during complex junction transits for a quick glance at where I need to be.
So I would like a recommendation or two on a good second hand newer faster replacement, I would be leaning towards something that I can see as a Windows drive rather than have to learn new procedures using software tools not available to me, seriously I still use Win7 and it does all I need. So my options are obviously limited but I do need something that handles big maps better.
TIA.

I’d say that if Windows 7 is still working perfectly for you, there’s no need to worry about a TomTom from the distant past.
I know the problem all too well; my old TomTom Rider v2 had the same issue—on winding roads, it would often lag several turns behind. That’s a thing of the past with the Rider 550. It’s time to upgrade; after all, the milkman doesn’t come to the door with a horse and cart anymore either.

We don't travel abroad every year, then our Go730 isn't fed up with some large 1.8Gb map on inner memory, or 3.8Gb Full Europe map on SD card.
We adjust the map size to our real needs.
A smallest 1Gb map is our choice : Nav3 1175 map + speedcams + Optimized.

Speedcams excepted, no permanent POI display is enabled.
No mp3 jukebox is played. No FM signal is sent to the car radio.
The whole calculation power is used for fast positioning (and recalculation when needed).

Otherwise our camper van is fitted with a Nav3 device (Start 25 or Via 120) running Europe Camper Nav3.

I want to continue using the Western Europe full maps as I live in mainland Europe and now travel cross border a lot again after a break of several years. I thought about loading the smaller maps for the individual countries but I would sooner have a seamless trip.
I could buy a new device with all the lifetime maps stuff but I would not give the game of tinkering with TomToms up for anything, it's hard going at times when I have not loaded new maps for ages but I still enjoy doing so.

You can find a Rider 550 on Marktplaats for less than €200. TomTom still provides it with the latest updates worldwide.
It can be used on a motorcycle as well as in a car.
Plus, you can experiment as much as you like with the older device.

There is a another option if you want to experiment a bit...

It sounds like your device is running short of RAM as coltrane1 is alluding to. If fully updated, the official navcore on your device should be 9.541?

If so, you could always try a modified version of the same navcore with a built in swap file which should help a lot with your issues. See the download link below and as always, do a full backup of your current setup in case you want to revert it:

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Credit goes to holyhead

I am using 9.541. Your post jogged a distant memory of looking over modified Navcores that utilised a swap file, a long time ago possibly Downunders work? I think I will give it a try, thanks for the heads up, I will certainly report back if there is an improvement, I dislike reading threads were advice is given for possible solutions and the OP just leaves the thread dead without confirmation of success or failure.
I still fancy two newer ones with larger screens, my eyes are getting old and also the rubberised casings are getting a bit yukky soft on the 720's, I regret not buying silicone skins when they were being sold for dead cheap as the units becaame obsolete.