id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc
23468	Performance issue with Validator tree window	GerdP	team	"Situation: Have a large dataset downloaded with overpass api and run validator with informational messages enabled. In my case I have > 560.000 entries in the tree and - probably most important - lots of results from TagChecker:
{{{
 Presets do not contain property key (529 359)
 Presets do not contain property value (3 081)
}}}
I've closed the validation layer as it slows down any zooming or paning drastically and I've zoomed in so that only a few nodes are visible. So far so good. JOSM is usable.
Steps to reproduce the performance issue:
1. Open new data layer (e.g. to download data from OSM and fix one important error), note that the validation tree windows is emptied (correct)
2. close the (small) data layer. Note that JOSM doesn't react for quite a while (17 secs in my case) before JOSM shows the validation results for the large dataset. (which didn't change)

I found out that most of the time is spent in `OsmValidator.getErrorsBySeverityMessageDescription()` which was written for #14704, esp. in `AlphanumComparator.compare()`. 

I wonder if there is a good reason to use this complex comparator instead of String.compare() which is much faster. I see difference in the order of messages but I wouldn't say one order is better than the other.

"	enhancement	closed	normal	24.02	Core validator		fixed	performance	simon04