Re: [Gimp-user] Large window size causes lag

[Jehan Pagès <jehan marmottard gmail com>]

Hi,

On Mon, Oct 6, 2014 at 2:40 PM, antiart <forums gimpusers com> wrote:
> I can confirm this issue. Exactly what I experienced and what I tried.
> It doesn't matter if the image is 100x100 or 10000x10000 pixels, only the WINDOW
> size makes the cursor slow.
> I have a new Lenovo z50-70, which is fairly fast and powerful, fresh install of
> Windows 8.1, all updated and with the newest drivers. I tried both, a wacom
> Bamboo Pen&Touch and a wacom Intuos 2, both have the lag. I also disabled/tested
> those Windows 8 tablet PC settings like hold-pen-to-right-click and the
> "flicks". Still lag.
> My partner suggested that the issue is related to the GPU, so i tried to force
> Gimp to use the Nvidia processor, and then I forced it to the "integrated
> processor". There was no difference. I also changed all my graphics settings to
> good performance and disabled the "fancy stuff".
>
> Interestingly I just noticed a very similar behavior in myPaint (version
> 1.1.0+gite06d414). The bigger the window, the more lag. This may be related
> (myPaint has an endless canvas, though). However, putting myPaint into
> Fullscreen kind of fixed the lagging. Sadly, this does not work for Gimp. There
> is still the same lag, no matter if fullscreen or maximized.
>
> And just for the record: None of the other painting application have this issue:
> SAI, Krita, Inkscape, ArtRage, Fresh Paint.
>
> > I am using Gimp 2.8.14 (latest version, just installed) with Windows
> > 8.1 and a Wacom Intuos tablet. When I maximise, or otherwise enlarge
> > the drawing window beyond around 30-40% of my screen size, the tool
> > cursor becomes very laggy. When using the paintbrush, for example, the
> > painted area, brush outline, and even the little markers on the ruler
> > that show the cursor position, lag significantly behind the penstroke.
> > With a smaller window, the tools work perfectly. There does not appear
> > to be any lag when using the mouse to draw, even for a maximised
> > window.
> >
> > I have increased the tile cache size to no effect, and when looking in
> > the task manager it appears that Gimp is only using around 150 Mb or
> > so. I have also tried turning the brush outline off (as suggested as
> > solutions to similar problems), but this also didn't work and I would
> > very much like to keep this switched on. The problem does not appear
> > to be affected by canvas size or the amount of the canvas displayed.

This is a known bug which has actually been introduced by a recent
version of libcairo.
See https://bugzilla.gnome.org/show_bug.cgi?id=736220

A solution for the time being is using an older libcairo. In an older
version of GIMP (2.8.10), save libcairo-2.dll (and maybe
libpixman-1-0.dll as well), then after updating to 2.8.14, replace the
newly installed DLLs by the 2 you saved. The lag bug should be gone.
At least that is what a user told us in the aforementionned bug report.

The actual bug will be fixed when a libcairo developer, or maybe one
of us, will look closer into this. I've been meaning to do this myself
as well, but never took the time for such a thing.

Jehan


> --
> antiart (via www.gimpusers.com/forums)
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