java.util.regex.Pattern class sluggishness

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Type: Performance Issue

Everytime I reference the java.util.regex.Pattern class in VSCode, it takes a solid 2 something seconds for the intellisense to catch up.

So for example, if I do:

Pattern., the tooltip that shows all the available methods takes a while to actually load in.

I don't have this issue with any other classes.

Extension version: 1.47.0
VS Code version: Code 1.105.1 (7d842fb85a0275a4a8e4d7e040d2625abbf7f084, 2025-10-14T22:33:36.618Z)
OS version: Windows_NT x64 10.0.26200
Modes:

System Info

Item	Value
CPUs	Intel(R) Core(TM) i5-14400F (16 x 2496)
GPU Status	2d_canvas: enabled 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_graphite: disabled_off trees_in_viz: disabled_off video_decode: enabled video_encode: enabled vulkan: disabled_off webgl: enabled webgl2: enabled webgpu: enabled webnn: disabled_off
Load (avg)	undefined
Memory (System)	31.84GB (20.14GB free)
Process Argv	--crash-reporter-id 33ebd6ef-09c3-4842-8740-f2a7cee857a7
Screen Reader	no
VM	0%

Process Info

CPU %	Mem MB	   PID	Process
    0	   138	 30928	code
    0	    32	  1776	   crashpad-handler
    0	   116	  5628	   gpu-process
    0	   284	 11140	window [1] (Running Extensions - test-java - Visual Studio Code)
    0	   114	 17352	file-watcher [1]
    0	   117	 20052	pty-host
    0	    91	  5276	     C:\WINDOWS\System32\WindowsPowerShell\v1.0\powershell.exe -noexit -command "try { . \"c:\Users\Jeremiah Wright\AppData\Local\Programs\Microsoft VS Code\resources\app\out\vs\workbench\contrib\terminal\common\scripts\shellIntegration.ps1\" } catch {}"
    0	     8	 27956	     conpty-agent
    0	    49	 23520	   utility-network-service
    0	   185	 30568	extension-host [1]
    0	   892	 25848	     "c:\Users\Jeremiah Wright\.vscode\extensions\redhat.java-1.47.0-win32-x64\jre\21.0.8-win32-x86_64\bin\java" --add-modules=ALL-SYSTEM --add-opens java.base/java.util=ALL-UNNAMED --add-opens java.base/java.lang=ALL-UNNAMED --add-opens java.base/sun.nio.fs=ALL-UNNAMED -Declipse.application=org.eclipse.jdt.ls.core.id1 -Dosgi.bundles.defaultStartLevel=4 -Declipse.product=org.eclipse.jdt.ls.core.product -Djava.import.generatesMetadataFilesAtProjectRoot=false -DDetectVMInstallationsJob.disabled=true -Dfile.encoding=utf8 -XX:+UseParallelGC -XX:GCTimeRatio=4 -XX:AdaptiveSizePolicyWeight=90 -Dsun.zip.disableMemoryMapping=true -Xmx2G -Xms100m -Xlog:disable "-javaagent:c:\Users\Jeremiah Wright\.vscode\extensions\redhat.java-1.47.0-win32-x64\lombok\lombok-1.18.39-4050.jar" -XX:+HeapDumpOnOutOfMemoryError "-XX:HeapDumpPath=c:\Users\Jeremiah Wright\AppData\Roaming\Code\User\workspaceStorage\9859a0f0e70baece4bfc91dbe050b5f3\redhat.java" -Daether.dependencyCollector.impl=bf -jar "c:\Users\Jeremiah Wright\.vscode\extensions\redhat.java-1.47.0-win32-x64\server\plugins\org.eclipse.equinox.launcher_1.7.100.v20251014-1222.jar" -configuration "c:\Users\Jeremiah Wright\AppData\Roaming\Code\User\globalStorage\redhat.java\1.47.0\config_win" -data "c:\Users\Jeremiah Wright\AppData\Roaming\Code\User\workspaceStorage\9859a0f0e70baece4bfc91dbe050b5f3\redhat.java\jdt_ws" --pipe=\\.\pipe\lsp-29f0832911fad8f693384ca7a1de459f-sock
    0	   134	 30760	shared-process

Workspace Info

|  Window (Running Extensions - test-java - Visual Studio Code)
|    Folder (test-java): 1 files
|      File types: java(1)
|      Conf files:;

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Reproduce the delay by opening a Java file in VS Code with the vscode-java extension and invoking completion after typing Pattern.. Compare completion responsiveness for java.util.regex.Pattern with other classes and investigate the Java language server process shown in the report. Done means the specific source of the roughly two-second delay is identified and completion responds normally.

Written by the indexing model from the issue text.

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