Mate,
86Gb written in one day, how big is your Inbox?
I would think that you inbox is big or it is checking for mail every minute. Or even re-indexing the inbox. Do you have any feeds configured in Thunderbird or is it just SMTP/IMAP?
With Thunderbird have you tried, to Repair and compact the Inbox?
I have about 3,600 email messages (Yea, I'm a bit lazy) so it uses about 400 Mb of memory on my Arch Linux system.
Have you looked at scripts to turn the Windows garbage off? Like the Telemetry. Chris Titus has some
HERE for Win 10, if that is what you are using.
Or you could use the Web Interface for email.
EDIT: I use Firefox and some add-ons to remove ad's and disable Java garbage. But also in Firefox Tools -> Browser Tools -> Task Manager shows the Memory and Energy used.
Hope this helps.