Yes there is a 102.3.0 64bit version. As for the rest, I have no idea as slowness has nothing to do with bitness.

Where I can I find the 64 bit version. The Thunderbird website gives only one version and does not mention 64 bit anywhere on the site.

The home page detects from your browser your operating system and offers the correct one for your system. It uses exactly the same technology as is used in this forum when it tells me you used Firefox version 105 to access this site running on windows 10 64 bit. So I really think the Free Download you are being offered will be a 64bit version. For instance I hover my mouse over the download button and it shows me in the status bar at the bottom on Firefox that it is a 64bit version to be downloaded. os=win64 to be precise.

However right under the Free Download button for your detected version is "systems and languages" which links to here https://www.thunderbird.net/en-US/thunderbird/all/ which lets you explicitly download anything you like for the current version.

Thank you! This solved my problem. Thunderbird automatically installed the 32 version of Thunderbird on 9/21/22, according to my Revo Uninstaller and confirmed in the About window of Thunderbird. However, you have led me to the correct version, which I have now installed.