Since I bought a Dell notebook with license for McAfee 5 years ago, I was happy with McAfee and even switched to McAfee Total Protection.
Although I could not easily find the detected items and found the user interface not user friendly enough, it did its job.
But a few days ago, I got 12.1 and that was not funny.
My PC was running extremely slow.
Clicking on a different email in Thunderbird took ages e.g.
I could not access my printer via USB, I could not connect an external disk via USB.
Shutting down my PC once ended with a blue screen after half an hour.
So I switched it off after 5 minutes by pressing the power button long enough to hard shutdown.
McAfee didn't even want to start scanning for viruses, the user interface allowed me to select it and then hung.
and followed these instructions to do a clean install of McAfee Total Protection 12.1
But the situation remained the same, no improvement at all.
Another trial to improve with McAfee Virtual Technician but it only found a language issue.
So I made the decision to stop waisting my time with investigating McAfee's 12.1.
I cleaned my PC and immediately my other three PC's to remove the last bit of McAfee.
And installed Microsoft Security Essentials.
I did a complete thorough scan with it and no virusses were found.
So I blame McAfee of having created Total Protection 12.1 that is drastically worse than their older releases.
I think they will lose a lot of customers with 12.1.
It's true some people are having issues with it but the major problems seem to be only on certain setups. There are some workarounds available for the Thunderbird issue, turning off email scanning for instance but you have a good point and sorry to see you go.
Technical Support are there to help you with this sort of thing and if the issue is escalated they will work through each issue with you to a happy conclusion, hopefully. They are free to contact by phone or online chat.
I have 12.1 installed on every OS that is currently supported and the only issue I've seen is a marginally slower startup and I know that they are aware of that. But then I don't use Thunderbird.
Thanks for posting and good luck ;-)