Fix errors is very slow

[GerdP]

See #13491, same steps and test data.
One problem here is that StyledMapRenderer.render() is executed for each "duplicate" node that is "fixed". On my machine that means that maybe one error is fixed per second.
Since all the duplicate nodes are marked with a yellow dot in the "Validation errors"
you will not see any change in the data layer. I don't know if it is intended to redraw, if yes, I think one redraw after each error class should be enough.
When I hide the layers the "fix" action for > 2000 errors is finished within 1 or 2 seconds.
This problem is also in r10916 and r10786 from ​http://josm.openstreetmap.de

[naoliv]

Seems to be #10676/#10101?

[GerdP]

Yes, it is related to the general slowness when "large" number of nodes are processed, but what I wanted to point out is that
there is no need to render the data after each change, at least it doesn't help the user in any way. I have no idea yet how complicated it is to change that. In fact, when I select all errors and click on Fix, I expect that all errors which can be fixed are fixed in a single action, so that a single undo gets me back to the original status.

[GerdP]

fixed with r14845