Aahh yes, I have heard of that Favourites, one of my devices has the same default shell & has it also but I've never bothered tapping it to see what it does.
[Only registered and activated users can see links. ] that's one for trucks on this site I found with a quick search, quite possibly there's others also.
No sorry I have no idea what might be making it laggy, being an older device it could be hardware failing, or any number of things I guess.
I've never had them go laggy like that, I've seen it only with Nav software running & that was caused by something I messed with myself, trying to edit a saved track file in Notepad++.
The software didn't like that at all & was very slow & froze up for minutes at a time, soon as I removed that particular track all was well again
To get a rough idea of the device's RAM size, the top one of your 3 pics shows looking at Windows CE in a file explorer, open the Control Panel.lnk by double tapping it, then double tap System, on the General tab it should have the RAM size displayed, for example the one I'm looking at now says Memory: 102088 KB RAM, which is roughly 100 MB.