id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc
20366	[partial patch] JOSM rendering is very slow especially on UHD displays	*Martin*	team	"After upgrading to UHD (4K) monitor I experience slow rendering in JOSM which makes mapping no more pleasant. Slowdown is higher if I move map outside of boundaries of downloaded data (see attached video) but it is also slow on normal editing, or with just panning signle layer of background imagery.

JOSM Version: 17447 (reproducible also on current josm-tested)
JRE: OpenJDK 16 (reproducible also on  OpenJDK 15)
OS: Debian Bullseye
HW: Radeon RX 5500 (HW acceleration enabled), AMD Ryzen 3900X, 64GB RAM

I run JOSM like this:

java -Dsun.java2d.uiScale=2 -Dsun.java2d.opengl=True -jar ~/josm-tested.jar

In the 2nd line of the console output I see:

OpenGL pipeline enabled for default config on screen 0

Parameter -Dsun.java2d.opengl=True actually makes no difference for the speed."	enhancement	new	normal		Core	latest		performance hidpi