Stardock Window blinds is VERY resource intensive. Or at least it used to be. I had used it in the past and quit using it because it was horrifically buggy and well known for sucking down system resources, unlike most these other shell utilities which merely make use of the configuration settings already part of the system.
I use OpenShell, 7StickyNotes, Rainmeter, and T-Clock to modify the look/feel of Windows. I recommended Windows Blinds because I thought he may be trying to change the "title bar" area of Windows. After discussing it by PM, I don't think that is his goal. I haven't used Windows Blinds on any of my real systems but may have tried it out for 10 minutes in a VM once or twice. I also haven't looked into OldNewExplorer yet either.
I use to love the "gadgets" from AddGadgets.com that everyone used in the older Windows sidebar. The Sidebar is still available for Win10 but it's unsecure and there are other issues with it. So I switched to RainMeter and found the same gadgets for them. https://forum.rainmeter.net/viewtopic.php?t=20699
T-Clock is straight forward, it allows you to easily modify the clock on the taskbar. You can add the spelled out date, change font settings, etc.
7StickyNotes is just another sticky notes clone. I like it because of it's lower RAM usage than a few others, and it's a real application, not one of these new fake Windows Apps.
Rainlender IS interesting. I've been using it for years now, and it's very configurable. You can import any preset holidays you want. You can do skins for the calender itself and put it wherever you want on any of the desktops. It keeps me from forgetting stuff because it's right there in plain sight where I get constant visual reminder of things that might usually slip my mind. Like appointments with clients, personal appointments, family member special dates, etc. I don't see myself ever NOT using it in the future unless it somehow becomes defunct.