[GTK4] Slow and choppy text scrolling with SWT_GTK4=1 #3583

Describe the bug

I just updated one of my Eclipse installations to 2026-09 and wanted to try the new GTK4 support. Unfortunately, it feels much slower in general, and in particular for text scrolling.

To Reproduce

1. Start Eclipse 2026-09.
2. Open some "large" (muliple pages) Java file.
3. Put the text cursor at the beginning of the file.
4. Press "down arrow" and keep it pressed.

I'm not sure how much it is visible on video, but here are two captures of this scenario, on the exact same Eclipse and workspace, the only difference being export SWT_GTK4=1 on the second one.

With Gtk3:

With SWT_GTK4=1:

Expected behavior

Scroll behavior should be (at least) as smooth and fast as before.

Environment:

1. Select the platform(s) on which the behavior is seen:

• • Windows
• • Linux (Fedora Linux 44 (Workstation Edition),
• • macOS

2. Additional OS info (e.g. OS version, Linux Desktop, etc)

3. JRE/JDK version

Temurin-25.0.4.1+1 (built-in JustJ)

Version since

Eclipse IDE for Eclipse Committers (includes Incubating components)
Version: 2026-09 (4.41.0)
Build id: 20260903-0720

Workaround (or) Additional context
Add any other context about the problem here.
Any known workarounds for the problem?