Re: [Evolution] Significant lag when composing emails

[Milan Crha <mcrha redhat com>]

On Tue, 2020-07-28 at 10:17 +0200, André Müller wrote:
> When I am writing in plaintext mode, I have this excessive lag: each
> character being delayed by some milliseconds and sometime more.
> Sometimes it freezes while typing and then in a burst all characters
> come at once. When I am writing in HTML mode, everything is fine.

        Hi,
that reminded me of some old issue, which I do not have a link to
handy, where had been reported similar lags and, if I recall it
correctly (my memory proves to be rusty and wrong in time), the problem
was related to assistive technologies, I think it was enough to have it
enabled and it could do some such weird things. I think one bug was
even about preventing to write certain letters into the composer
message body. And there was something about libharfbuzz too, though it
might be for the message preview only.

I do not say it's only it, there can be multiple problems. If the lag
is long enough to switch to a terminal and invoke a command there
(especially when the Evolution itself is also frozen), then you can
prepare a command like this:

   $ gdb --batch --ex "t a a bt" -pid=`pidof evolution` &>bt.txt

to see what Evolution does (or waits for) in time of it being frozen.
Please check the bt.txt for any private information, like passwords,
email address, server addresses,... I usually search for "pass" at
least (quotes for clarity only), before sharing it anywhere, because it
can contain such information. Also, to have usable backtrace, make sure
you have installed also debuginfo (dbg) packages for evolution-data-
server and evolution (your Ubuntu splits these into several packages,
one for each subpart of the evolution/-data-server; I do not know how
to effectively search for the related packages in your system, I'm
sorry).

In case the Evolution process is not frozen, then the lag is caused by
one of the WebKitWebProcess processes, the one associated to the
message composer. It might be the latest, as the first composer window
creates one (and the last composer window closes it when it's closed).
It might be waiting for something, probably.

You can also try to turn off spell checking, uncheck everything in the
Edit->Current Languages in the composer window.

I do not know whether anything from the above will be helpful for you,
to debug possible cause of the problem.
        Bye,
        Milan