Editor to become unresponsive when both Highlight Matching Tag and Overtype extensions are enabled

[rbolsius]

Type: Bug

When the Highlight Matching Tag extension is enabled, VS Code becomes unresponsive to keypresses when inserting new text into medium to large XML files (even 2MB is too large for the extension to handle). Some keyboard actions like backspace and delete are still responsive, but typing any new characters results in nothing being inserted.

In the developer tools console there are many messages like the following.

INFO UNRESPONSIVE extension host: starting to profile NOW

Although the console does not name the Highlight Matching Tag extension as the culprit, the "Help: Start Extension Bisect" command reveals this extension to be the cause. When the extension is disabled, text can be inserted into the XML document.

Extension version: 0.11.0
VS Code version: Code 1.77.1 (b7886d7461186a5eac768481578c1d7ca80e2d21, 2023-04-04T23:21:11.906Z)
OS version: Windows_NT x64 10.0.19045
Modes:
Sandboxed: No

System Info

Item	Value
CPUs	Intel(R) Core(TM) i7-6700HQ CPU @ 2.60GHz (8 x 2592)
GPU Status	2d_canvas: enabled canvas_oop_rasterization: disabled_off direct_rendering_display_compositor: disabled_off_ok gpu_compositing: enabled multiple_raster_threads: enabled_on opengl: enabled_on rasterization: enabled raw_draw: disabled_off_ok skia_renderer: enabled_on video_decode: enabled video_encode: enabled vulkan: disabled_off webgl: enabled webgl2: enabled webgpu: disabled_off
Load (avg)	undefined
Memory (System)	15.83GB (4.92GB free)
Process Argv
Screen Reader	no
VM	0%

[rbolsius]

I did a bit more digging and found that this issue appears to be an incompatibility between this extension and the Overtype extension.

When either one of these extensions is enabled by itself, VS code responds immediately to keystrokes to insert characters when editing larger XML files. However, when just these two extensions are enabled, even XML files around 256KB begin to show significant delays when typing.

I can provide sample XML files if needed, but I think any XML file over 1MB in size will be enough to reproduce the delay.

[rbolsius]

Since it is not clear which extension is at fault, I have also created the following issue against the Overtype extension.

DrMerfy/vscode-overtype#38