[Parti-discuss] local xpra sessions laggy as heck

[Nathaniel Smith]

On Thu, May 28, 2009 at 2:52 PM, Keith Bronstrup <keith at bronstrup.com> wrote:
> Just to clarify, both the copies of xpra (daemon and client) are running on
> the same machine, with the client being forwarded via PuTTY (SSH) to an
> instance of Xming.

This isn't a configuration that I really took into account when
designing xpra, so I'm not surprised if it doesn't work well... you
may end up combining the worst aspects of both X and xpra's respective
protocols. (Drawing over X can be efficient because you can send
commands like "draw a line" and "copy region A to region B" (very
useful for scrolling), while xpra doesn't have that kind of high-level
semantic knowledge about what the app is doing so it just sends big
blocks of pixels for everything. OTOH, X's protocol tends to be much
more sensitive to high-latency links.)

That said, I don't know why it would be *that* bad; the way the xpra
client uses X shouldn't be making *that* many round trips, and a quick
skim of the source doesn't reveal any obvious problems (unless maybe
you're resizing your window a bunch, but I assume not). To debug
further, I'd probably want to examine -d protocol and xtrace logs for
the client, but I'm not sure how much of a priority I'll be able to
make this.

(There are also some patches on the list for running the xpra client
under windows directly, though IIRC they don't have support for ssh
yet. When windows support gets finished then you'll also have that
option.)

-- Nathaniel