To diagnose problems with Thunderbird, try the following:

• Restart the operating system in safe mode with Networking. This loads only the very basics needed to start your computer while enabling an Internet connection. Click on your operating system for instructions on how to start in safe mode: Windows 8, Windows 7, Windows Vista, Windows XP, OSX

If safe mode for the operating system fixes the issue, there's other software in your computer that's causing problems. Possibilities include but not limited to: AV scanning, virus/malware, background downloads such as program updates.

Thanks Matt, safe mode allowed T-bird to run with normal quickness. When I restarted in normal mode, T-bird was again slow and "jerky"; so I tried shrinking the window size to 1/4 screen (so I could see Task Manager too). The speed was much faster. Could it be that v38.0.1 has a greater demand on my video card (PNY GeForce VCG62256AEB)? Task manager showed cpu usage was, by far, mostly T-bird.

You could try turning off the hardware acceleration in the tools menu (alt+T) > options > advanced > general. But I don't think it will be the issue as safe mode does not turn that off.

I would be more inclined to suggest an exception for your profile folder from anti virus scanning. (Delay being Thunderbird and the anti virus arguing over access to files.)

Have a look here https://wiki.mozilla.org/Thunderbird:Testing:Antivirus_Related_Performance_Issues

We probably have your anti virus listed as I am not aware of one that does not occasionally mess up on a new version.

Regardless, let me know how you get on. I learn from these things as well.

Hi Matt, Only T-bird is slow to respond to a Click or Scroll; other apps run ok. Tried turning off the Acceleration - no help. Added the T-bird Profile folder to Exceptions in MSE (the only AV I have running). - no help. Still, could it be my graphics card as Safe Mode uses lower resolution? I haven't loaded any updates or new apps since upgrading to v30.0.1. I sure appreciate your time! TED

Hi Matt, More info that may help. Everything while using T-bird has a delay. If a scrolling click there is a first move of about 10% (half second later) then a second move of about 20% (another half second) then the final mode of 70% a half second later. When writing an E-mail, characters are quick but <Enter> response is delayed by the half second. It seems that all other operations with T-bird (selecting another e-mail to view, switching applications to T-bird, Menu etc.) there is always the half second When leaving T-bird to another application there is no delay.

Ted, open a write windows and type quickly. If your a poor typist type rubbish. Does Thunderbird keep up or does the typing stop or appear on screen in batches, or keep typing after you stop to catch up?.

Please add the troubleshooting information to your post To find the Troubleshooting information:

• Open Help (or click on three-line-icon and select Help)
• Choose Troubleshooting Information
• Use the button Copy to clipboard to select all. Do not check box "Include account names"!
• Paste this in your post.

Matt, typing does keep up with me (even at rubbish speed). Here is clipboard:

 Application Basics

   Name: Thunderbird
   Version: 38.0.1
   User Agent: Mozilla/5.0 (Windows NT 6.1; rv:38.0) Gecko/20100101 Thunderbird/38.0.1
   Profile Folder: Show Folder

             (Local drive)
   Application Build ID: 20150608103712
   Enabled Plugins: about:plugins
   Build Configuration: about:buildconfig
   Memory Use: about:memory

 Mail and News Accounts
   account1:
     INCOMING: account1, , (pop3) inbound.att.net:995, SSL, passwordCleartext
     OUTGOING: outbound.att.net:465, SSL, passwordCleartext, true

   account2:
     INCOMING: account2, , (none) Local Folders, plain, passwordCleartext

 Crash Reports

 Extensions

 Important Modified Preferences

   Name: Value

     accessibility.typeaheadfind.flashBar: 0
     browser.cache.disk.capacity: 358400
     browser.cache.disk.smart_size_cached_value: 358400
     browser.cache.disk.smart_size.first_run: false
     browser.cache.disk.smart_size.use_old_max: false
     extensions.lastAppVersion: 38.0.1
     font.internaluseonly.changed: true
     font.name.monospace.el: Consolas
     font.name.monospace.tr: Consolas
     font.name.monospace.x-baltic: Consolas
     font.name.monospace.x-central-euro: Consolas
     font.name.monospace.x-cyrillic: Consolas
     font.name.monospace.x-unicode: Consolas
     font.name.monospace.x-western: Consolas
     font.name.sans-serif.el: Calibri
     font.name.sans-serif.tr: Calibri
     font.name.sans-serif.x-baltic: Calibri
     font.name.sans-serif.x-central-euro: Calibri
     font.name.sans-serif.x-cyrillic: Calibri
     font.name.sans-serif.x-unicode: Calibri
     font.name.sans-serif.x-western: Calibri
     font.name.serif.el: Cambria
     font.name.serif.tr: Cambria
     font.name.serif.x-baltic: Cambria
     font.name.serif.x-central-euro: Cambria
     font.name.serif.x-cyrillic: Cambria
     font.name.serif.x-unicode: Cambria
     font.name.serif.x-western: Cambria
     font.size.fixed.el: 14
     font.size.fixed.tr: 14
     font.size.fixed.x-baltic: 14
     font.size.fixed.x-central-euro: 14
     font.size.fixed.x-cyrillic: 14
     font.size.fixed.x-unicode: 14
     font.size.fixed.x-western: 14
     font.size.variable.el: 17
     font.size.variable.tr: 17
     font.size.variable.x-baltic: 17
     font.size.variable.x-central-euro: 17
     font.size.variable.x-cyrillic: 17
     font.size.variable.x-unicode: 17
     font.size.variable.x-western: 17
     mail.openMessageBehavior.version: 1
     mail.winsearch.firstRunDone: true
     mailnews.database.global.datastore.id: 1c72edb2-d09e-4411-b5c3-e0add81bd97
     network.cookie.prefsMigrated: true
     network.predictor.cleaned-up: true
     places.database.lastMaintenance: 1436546700
     places.history.expiration.transient_current_max_pages: 40255
     plugin.importedState: true

 Graphics

     Adapter Description: NVIDIA GeForce 6200 (Prerelease - WDDM 1.0)
     Vendor ID: 0x10de
     Device ID: 0x0221
     Adapter RAM: 256
     Adapter Drivers: nvd3dum nvwgf2um
     Driver Version: 8.15.11.8171
     Driver Date: 2-26-2009
     Direct2D Enabled: Blocked for your graphics driver version. Try updating your graphics driver to version 182.65 or newer.
     DirectWrite Enabled: false (6.2.9200.17292)
     ClearType Parameters: ClearType parameters not found
     WebGL Renderer: Blocked for your graphics driver version. Try updating your graphics driver to version 182.65 or newer.
     GPU Accelerated Windows: 2/2 Direct3D 11 WARP

     AzureCanvasBackend: skia
     AzureSkiaAccelerated: 0
     AzureFallbackCanvasBackend: cairo
     AzureContentBackend: cairo

 JavaScript

 Incremental GC: 1

 Accessibility

   Activated: 0
   Prevent Accessibility: 0

 Library Versions

     Expected minimum version
     Version in use

     NSPR
     4.10.8
     4.10.8

     NSS
     3.18.1 Basic ECC
     3.18.1 Basic ECC

     NSS Util
     3.18.1
     3.18.1

     NSS SSL
     3.18.1 Basic ECC
     3.18.1 Basic ECC

     NSS S/MIME
     3.18.1 Basic ECC
     3.18.1 Basic ECC

Hi Matt, indeed there is a typing delay when there is a CR even if T-bird does one for me (if my line over runs). Changing screens within T-bird has the delay too. Thanks again for your attention. TED

Hi Matt, there is also a delay when switching to the T-bird screen from another application (T-bird already running). All other programs run fine. Was the "Troubleshooting Information" sent from my clipboard helpful? TED