Rated 3 out of 5 stars

At each reminder, it makes high CPU and I have to close TB

This review is for a previous version of the add-on (1.0.0). 

Hi,
I'm sad to hear this. This is not the intended behaviour of mailmindr, and I take the review seriously.
It seems that the root cause for this behaviour is a lot of accounts, mails and/or folders, so mailmindr needs time for looking up the follow-up'd mail. I'm working on a solution on this issue, but I have to first check the behaviour for the next Thunderbird version which is announced for this summer, so the solution for this problem doesn't last only until the next Thunderbird version is out.
Thanks for reaching out - if you're facing more issues, just let me know: hello[at]mailmindr.net