There are 64 bit versions. https://www.thunderbird.net/en-US/thunderbird/all/

Thunderbird has been running @ 32 bit ever since it inception. Now that windows 7 and 10 are running @ 64 bit why hasn't Thunderbird been released for 64 bit OS? I know 32 bit applications will run on 64 bit system as your doing that now. But staying @ 32 bits has it drawbacks mainly because when memory fetch operations are done it takes 2 operations for 32 bit application to do complete that instead of 64 bit which only take 1 operation. But I fear that your hurting memory and usage of memory. I am still experiencing pauses on my Windows 10 laptop. I have 8 GB of memory as much as I like to go 16 GB I don't think that will help any either. You have 64 bit for other such as Linux and Mac OS so what the hold up here? Why have you not made that move to 64 bit on Windows?

If you are concerned about memory usage on your memory constrained laptop, surely you don't want to run 64bit Thunderbird?

Also, your cited memory fetch drawback, if it exists, isn't going to be perceptible. It's also not listed at https://softwareengineering.stackexchange.com/questions/315810/is-there-a-good-reason-to-run-32-bit-software-instead-of-64-bit-on-64-bit-machin which typically has very reliable information.

But, you've speculated on solutions before the problem "I am still experiencing pauses" is clearly understood. The problem is the starting point. The typical first step is... Start *Windows'* safe mode with networking enabled - win10 https://support.microsoft.com/en-us/help/12376/windows-10-start-your-pc-in-safe-mode Still In Windows safe mode, start thunderbird in safe mode - https://support.mozilla.org/kb/safe-mode-thunderbird

Does problem go away?

Thanks but provided the following: https://www.thunderbird.net/en-US/thunderbird/all/

I have install the 64 bit version. My question to you why keep 32 bit. The only reason is older OS that does not support 64 bit. That the ONLY reason.

To answer your question, No going to safe mode does NOT solve the issue. Since I have installed 64 bit version. I will see how this runs. BTW, i have 35 years of IT experience. I know the differences. But I appreciate your feedback.

re :The only reason is older OS that does not support 64 bit. That the ONLY reason.

Not the only reason. Some people use other programs that interact with Thunderbird and those other programs may only work with 32bit. So they would need a 32bit version of Thunderbird in order for compatibility.