Major Improvements in Scrolling Performance for Vim GTK3 Wayland

A new patch has been released to significantly improve scrolling performance in the GTK3 Wayland backend of the Vim editor. According to Phoronix, Vim developer Dezza submitted a pull request last week to introduce deferred dirty redraw processing for the GTK3 Wayland backend. This change reduces the rendering load during scrolling and noticeably decreases CPU usage.

Details of the Pull Request

This pull request fundamentally revises the redraw processing mechanism in Vim’s GTK3 Wayland backend. In its previous implementation, micro-redraws queued by functions such as gui_gtk_draw_string_ext were excessively executed every time a key was pressed or a scroll action was performed.

In the pull request, Dezza explains the impact of this change on end-users as follows: “As a result, scrolling becomes faster and almost smooth, and CPU usage drops significantly because key inputs, especially repeated key presses or scroll keys like PgUp/Ctrl+B, no longer simultaneously pump excessive redraws queued by functions like gui_gtk_draw_string_ext.”

As this explanation suggests, the core issue lay in the “synchronous coupling of key inputs and rendering processes.” In the previous implementation, rendering would be triggered immediately every time a key was pressed, leading to a large number of redraws in a short period, which placed a significant load on the CPU. The new implementation delays these redraws and processes them in batches at necessary intervals, thereby reducing unnecessary computation.

When opening the pull request, Dezza described it as “a major milestone in performance on GTK3 with Wayland.”

Challenges for Vim on Wayland

Wayland is a display server protocol developed as a successor to the X Window System. Designed with security and performance improvements in mind, it features a different rendering model from the traditional X11 environment, requiring adaptation on the application side.

Vim has long provided a GUI interface through toolkits like GTK2 and GTK3. Rendering in Wayland environments is handled via the GTK3 Wayland backend, but performance issues, particularly in terms of rendering delays and high CPU usage during scrolling, have been a common complaint among users.

This patch directly addresses these longstanding issues. Vim remains a beloved editor among many developers, and improving its scrolling performance, a fundamental operation, directly enhances user experience.

Relationship with Migration to GTK4

Interestingly, this performance improvement for the GTK3 Wayland backend comes at a time when the Vim community is working on maturing its GTK4 support. According to Phoronix, this improvement is seen as “a fantastic performance enhancement for GTK3 Wayland-based Vim, even as work on GTK4 support continues to progress.”

GTK4, the successor to GTK3, boasts a more modern rendering engine and native support for Wayland. However, transitioning to GTK4 will take time. Given that many users still rely on GTK3 environments, improving the existing GTK3 backend is a practical approach to enhance short-term user experience.

Technical Significance

The technique of deferred dirty redraw is a standard optimization method in GUI application development. Instead of immediately rendering areas that require updates, the method introduces a delay and processes multiple redraw requests in batches, reducing CPU load.

Applying this technique to Vim is expected to improve performance in several scenarios.

First, continuous scrolling operations. In the past, rendering for each line was triggered individually during continuous scrolling. With the new implementation, these renderings are batched, reducing CPU usage.

Second, during key-repeat actions. In the previous implementation, rendering was triggered every time a key repeat occurred during continuous text input, which could lead to delays in cursor movement and character display. With the new improvement, key input and rendering processes are decoupled, enabling a smoother input experience.

Editorial Opinion

In the short term, this improvement is expected to enhance the everyday editing experience for developers using Vim in a Wayland environment. The significant reduction in CPU usage, particularly when working with large files or during extended coding sessions, will be a notable advantage for users, especially those on battery-powered laptops. If this patch is merged into Vim’s mainline code, it is likely to be widely adopted through the packages of major Linux distributions.

From a long-term perspective, this improvement can be seen as an example of the overall maturation of the Wayland ecosystem. Enabling a legacy application like Vim to perform efficiently in a Wayland environment could encourage further adoption of Wayland. As the Linux desktop environment continues transitioning from X11, the Wayland compatibility of major applications will play a key role in improving platform reliability.

The editorial team also notes the significance of this improvement in the context of GTK4 migration. Enhancing the GTK3 backend while efforts to support GTK4 are ongoing demonstrates a commitment to improving the current user experience while laying the groundwork for future developments.

References

• Phoronix: Vim Patches Yielding Faster GTK3 Wayland Performance: “Major Milestone” — Published on 2026-06-28