Scrolling my list of email has always been dog slow in Thunderbird, perhaps 1 second to update screen for each scroll refresh – like a VNC session to 12,000 miles away. Today I realized that scrolling is LIGHTNING fast, wow!!! Something has been fixed. Maybe relayed to the font stuff recently?
Having been using SeaMonkey since its inception, and managing 19283 mails in one local folder at the moment (a folder that slowly grew over years), I’ve never experienced any lag myself. I mention this because my understanding is that SeaMonkey borrows its mail client from Thunderbird sources (as it borrows its browser part from Firefox sources).
I am something of a typophile so I’ve regularly used Infinality-modded FreeType libs with all improvements enabled — which looked perfect to me but was said to be comparatively slow text rendering, especially compared to standard FreeType. Even then I’ve never noticed any lag or delay or stuttering, scrolling through thousands of mails.
Do you have many mails with exotic multi-byte characters in the subject line? Or emoji? Anything non-ASCII? (Come to think of it, I do too, and it hasn’t slowed down SeaMonkey). Are your mails online (via IMAP4), or are you scrolling through a local folder?
If you’re feeling investigative, you could try and
- do a virtual install of an older Linux and older Thunderbird
- import your current mails into that older Thunderbird
- install some version of SeaMonkey and import the same mails
- compare scrolling behaviors
I’ve stumbled upon an old Mozillazine thread where slow scrolling was improved during Safe Mode activated, but that was back in 2011. Another thread recommended modifying some configuration parameters (general.smoothScroll.mouseWheel.durationMaxMS and mousewheel.enable_pixel_scrolling) that influence scrolling behavior.
Oh well, glad it improved on its own via update. Cheers!