JOSM very low FPS on 4K Screens

General talk
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I’m running JOSM on my Mac Studio, 96GB RAM, tons of CPU cores.

But JOSM is just running slow, making it barely usable for me.

Here’s the same but with a smaller window, and the performance seems to improve a lot, but still a little laggy.

I had the same on Windows 10. It’s one of the reasons I use iD mostly, it just performs way better.

Is there a way to improve that (massively)? Am I doing something wrong? Can I change some setting? Enable GPU rendering or something?

2

Might be a Java issue (it’s known to cause performance drops in lots of situations)

Oh and I don’t think there’s a GPU rendering option in JOSM (idk I haven’t used it in ages)

Edit: I KNEW SimonPoole would react with a :-1:t2:

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3

Have you looked at Available Reports – JOSM ? Maybe it is already reported and discussed there?

4

Possibly this?

I’ve gotten a newer computer since commenting there four years ago and now I don’t notice this issue as much. Presumably the faster hardware results in less lag through brute force. Looks like some improvements may be in the works.

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5

Give josm more ram on jvm because Java is heavy on ram.

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6

I haven’t but looks like I should open a ticket

7

Made a ticket: #24585 (JOSM is running with low FPS on 4K screens.) – JOSM

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I think part of the problem you are seeing is down to the fact that JOSM, once you start creating a new feature, always attempts to snap to the nearest vertex. This will require the app to continuously calculate the proximity of nodes to the cursor’s position, a thing I could well see costing a lot more time with lots of nodes in the display’s extent.

I don’t know if JOSM builds some kind of in-memory spatial index of the features it loads, but it might well not be doing that assuming most people will load limited extents.