slowdown if gpx is above data layer

[richlv]

"latest" 4002.
if a gpx is above data layer, josm becomes much slower (panning, adding nodes/ways etc).
if the gpx is moved below data layer, performance improves a lot.

possibly more visible with larger gpx & data layers, definitely observable with 1mb gpx & large-ish data layer.

[bastiK]

This is by design. The lower layers are cached as a whole but we cannot cache each layer separately.

[richlv]

hmm. so in this specific case, what causes the slowdown ?
large dataset or large gpx ?
would having anything on top of larger data layer cause slowdown ?

[bastiK]

Size of data layer does not matter as long as you have zoomed in. I guess it caused by re-draw of gpx layer when it is on top of data layer.

[bastiK]

to investigate, hide certain layers and pan. observe the delay.

[richlv]

i tried hiding them before - hiding either gpx or data layer makes it fast.

looks like "large dataset" definitely is not the cause here - it's dog slow with just 234 nodes & 51 way (no relations).

zoomed out also is not - i'm zoomed in so the scale bar shows 10m, and panning is very slow (like a second delay for any movement...)

so i tried with a smaller gpx - 170kb uncompressed. it's still very slow.

mmmmmmm. i do believe there is a regression, though ;)

just tried with josm 3701 and i don't see any slowdown with the exact same dataset and exact same gpx.

3966 also has the problem. 3751 doesn't start up for me anymore.

so this seems to have regressed between 3701 and 3966

[richlv]

reopening so that this is not lost

[bastiK]

can you check if antialiasing of gpx layer is different when it is on top? This is the case for me and could be the cause for your problem.

[bastiK]

In [4021/josm]:

turn off antialiasing for gpx layers by default. Too slow because gpx layer does not use quadbucket. (see #6197)

[richlv]

yes, it indeed was. and i see that 4021 should help me - thanks :)

i'll wait for the next "testing" to be available.

[anonymous]

hooray. 4021 is back to the speed :)