[Python Environments] Virtual environment activation is slow

[cecheta]

Type: Performance Issue

Activating the virtual environment seems to take a long time (about 5 seconds) after opening a new shell. This is quite annoying, as the source command that gets executed in the shell will interrupt any other command that you are currently trying to write.

Environment Information

Extension Version: 1.12.0
Python Extension Version: 2025.18.0

Registered Environment Managers (4):
  - ms-python.python:system (Global)
  - ms-python.python:venv (venv)
  - ms-python.python:pyenv (PyEnv)
  - ms-python.python:poetry (Poetry)

Total Available Environments: 6
Environment Details:
  1. Python 3.13.9 (homebrew) (3.13.9.final.0) - /home/linuxbrew/.linuxbrew/bin/python3.13
  2. Python 3.12.3 (3.12.3.final.0) - /bin/python3
  3. Python 3.12.3 (3.12.3.final.0) - /usr/bin/python3
  4. .venv (3.13.9) (3.13.9) - /home/cecheta/Code/playground/.venv/bin/python
  5. pyenv (3.13.9) (3.13.9) - /home/cecheta/.pyenv/versions/3.13.9
  6. pyenv (3.12.9) (3.12.9) - /home/cecheta/.pyenv/versions/3.12.9

Python Projects (1):
  1. /home/cecheta/Code/playground
     Environment: .venv (3.13.9)

Extension Settings:
  Default Environment Manager: ms-python.python:venv
  Default Package Manager: ms-python.python:pip
Auto-activation is "command". Activation based on first 'py-env.terminal.autoActivationType' setting which is 'command' and 'python.terminal.activateEnvironment' if the first is undefined which is 'true'.

Extension version: 1.12.0
VS Code version: Code 1.106.2 (1e3c50d64110be466c0b4a45222e81d2c9352888, 2025-11-19T16:56:50.023Z)
OS version: Windows_NT x64 10.0.26200
Modes:
Connection to 'dev-container+7b22686f737450617468223a225c5c5c5c77736c2e6c6f63616c686f73745c5c5562756e74755c5c686f6d655c5c636563686574615c5c436f64655c5c706c617967726f756e645c5c7265636f6d6d656e6465722d617263686974656374757265222c226c6f63616c446f636b6572223a66616c73652c22636f6e66696746696c65223a7b22246d6964223a312c2270617468223a222f686f6d652f636563686574612f436f64652f706c617967726f756e642f7265636f6d6d656e6465722d6172636869746563747572652f2e646576636f6e7461696e65722f646576636f6e7461696e65722e6a736f6e222c22736368656d65223a227673636f64652d66696c65486f7374227d7d' could not be established
Remote OS version: Linux x64 5.15.167.4-microsoft-standard-WSL2

System Info

Item	Value
CPUs	12th Gen Intel(R) Core(TM) i7-1265U (12 x 2688)
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)	31.83GB (7.15GB free)
Process Argv	--crash-reporter-id 392977bc-6401-4ec2-bcbf-cace57dee1d0
Screen Reader	no
VM	0%

Connection to 'dev-container+7b22686f737450617468223a225c5c5c5c77736c2e6c6f63616c686f73745c5c5562756e74755c5c686f6d655c5c636563686574615c5c436f64655c5c706c617967726f756e645c5c7265636f6d6d656e6465722d617263686974656374757265222c226c6f63616c446f636b6572223a66616c73652c22636f6e66696746696c65223a7b22246d6964223a312c2270617468223a222f686f6d652f636563686574612f436f64652f706c617967726f756e642f7265636f6d6d656e6465722d6172636869746563747572652f2e646576636f6e7461696e65722f646576636f6e7461696e65722e6a736f6e222c22736368656d65223a227673636f64652d66696c65486f7374227d7d' could not be established

Item	Value
Remote	WSL: Ubuntu
OS	Linux x64 5.15.167.4-microsoft-standard-WSL2
CPUs	12th Gen Intel(R) Core(TM) i7-1265U (12 x 0)
Memory (System)	15.54GB (10.68GB free)
VM	0%

Process Info

CPU %	Mem MB	   PID	Process
    0	   179	 16676	code
    0	   126	  2560	file-watcher [8]
    0	   278	  5348	window [1] (.env - recommender-architecture [Dev Container: Recs-explore] - Visual Studio Code)
    0	    32	  5704	   crashpad-handler
    0	   238	  9424	shared-process
    0	   223	 15044	   gpu-process
    0	   245	 15888	extension-host [8]
    0	    10	 11760	     C:\WINDOWS\system32\wsl.exe -d ubuntu -e /bin/sh -c "cd '/home/cecheta/Code/playground' && /bin/sh"
    0	     9	 19812	       C:\WINDOWS\system32\conhost.exe 0x4
    0	    15	 28420	       C:\WINDOWS\system32\wsl.exe -d ubuntu -e /bin/sh -c "cd '/home/cecheta/Code/playground' && /bin/sh"
    0	    14	 24632	          --distro-id {138b298a-6910-4cd5-8bdc-e4d0710d0a4b} --vm-id {d0ee5567-ee97-41d5-b507-cc3939d15410} --handle 940 --event 976 --parent 980
    0	    12	 33624	           C:\WINDOWS\system32\conhost.exe 0x4
    0	   110	 29184	     electron-nodejs (wslDaemon.js )
    2	   374	 16240	window [8] (● <!-- Please describe the issue you're ex • Untitled-1 - playground [WSL: Ubuntu] - Visual Studio Code)
    0	    98	 20236	file-watcher [1]
    0	    53	 22784	   utility-network-service
    0	   128	 23620	pty-host
    0	   211	 28788	extension-host [1]
    0	    99	 14488	     "C:\Users\cecheta\AppData\Local\Programs\Microsoft VS Code\Code.exe" c:\Users\cecheta\.vscode\extensions\ms-vscode-remote.remote-containers-0.431.1\dist\shutdown\shutdownMonitorProcess \\.\pipe\vscode-remote-containers-034f4264-7efc-4371-8bda-0757af2bcc37-sock singleContainer Debug c:\Users\cecheta\AppData\Roaming\Code\logs\20251120T101323\window1\exthost\ms-vscode-remote.remote-containers 1763633612201
    0	    10	 33304	     C:\WINDOWS\system32\wsl.exe -d Ubuntu -e /bin/sh -c "cd '/home/cecheta/Code/playground/recommender-architecture' && /bin/sh"
    0	    15	 26740	       C:\WINDOWS\system32\wsl.exe -d Ubuntu -e /bin/sh -c "cd '/home/cecheta/Code/playground/recommender-architecture' && /bin/sh"
    0	    14	  5780	          --distro-id {138b298a-6910-4cd5-8bdc-e4d0710d0a4b} --vm-id {d0ee5567-ee97-41d5-b507-cc3939d15410} --handle 928 --event 960 --parent 964
    0	    12	 33200	           C:\WINDOWS\system32\conhost.exe 0x4
    0	     9	 30432	       C:\WINDOWS\system32\conhost.exe 0x4
Connection to 'dev-container+7b22686f737450617468223a225c5c5c5c77736c2e6c6f63616c686f73745c5c5562756e74755c5c686f6d655c5c636563686574615c5c436f64655c5c706c617967726f756e645c5c7265636f6d6d656e6465722d617263686974656374757265222c226c6f63616c446f636b6572223a66616c73652c22636f6e66696746696c65223a7b22246d6964223a312c2270617468223a222f686f6d652f636563686574612f436f64652f706c617967726f756e642f7265636f6d6d656e6465722d6172636869746563747572652f2e646576636f6e7461696e65722f646576636f6e7461696e65722e6a736f6e222c22736368656d65223a227673636f64652d66696c65486f7374227d7d' could not be established
Connection to 'WSL: Ubuntu' could not be established  cat: /proc/23154/stat: No such file or directory
/home/cecheta/.vscode-server/bin/1e3c50d64110be466c0b4a45222e81d2c9352888/out/vs/base/node/cpuUsage.sh: line 27: let: PROCESS_TIME_BEFORE=+: syntax error: operand expected (error token is "+")

Workspace Info

Connection to 'dev-container+7b22686f737450617468223a225c5c5c5c77736c2e6c6f63616c686f73745c5c5562756e74755c5c686f6d655c5c636563686574615c5c436f64655c5c706c617967726f756e645c5c7265636f6d6d656e6465722d617263686974656374757265222c226c6f63616c446f636b6572223a66616c73652c22636f6e66696746696c65223a7b22246d6964223a312c2270617468223a222f686f6d652f636563686574612f436f64652f706c617967726f756e642f7265636f6d6d656e6465722d6172636869746563747572652f2e646576636f6e7461696e65722f646576636f6e7461696e65722e6a736f6e222c22736368656d65223a227673636f64652d66696c65486f7374227d7d' could not be established
Connection to 'WSL: Ubuntu' could not be established  cat: /proc/23154/stat: No such file or directory
/home/cecheta/.vscode-server/bin/1e3c50d64110be466c0b4a45222e81d2c9352888/out/vs/base/node/cpuUsage.sh: line 27: let: PROCESS_TIME_BEFORE=+: syntax error: operand expected (error token is "+")
;

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[stevbev]

The gif cecheta posted is a great visual of the problem. I have the same exact problem on MacOS. There seems to be a ~5 second delay from the time the terminal window is opened until the source command is executed. I have done some testing and this does not appear to be an execution delay in the source command, it appears to be an internal VSCode delay after the terminal window is opened and before starting execution of source.

I don't know the exact timeline when this issue began occurring. It appears to have started within the last 2 weeks and likely last week.

OS: MacOS 15.7.2 arm64
Python: 3.13.9
VSCode: 1.106.2

[mrakhror]

Same here, it is really annoying.

[karthiknadig]

Please try setting python-envs.terminal.autoActivationType to shellStartup. That uses a different mechanism, it is experimental but give it a try. First time might be slow until it finds an environment, it will use the above move, but subsequent terminal creation, and even VS Code reload should be faster.

Notes on this:
For most cases this works with Shell Integration feature in VS Code. If SI is off or a terminal does not support SI then we update shell startup script to activate environments only when opened in VS Code. In case, shell does not support dynamic evals like nu it will fall back to command activation.

[cecheta]

It seems like I had Shell Integration disabled because I had modified terminal.integrated.profiles.linux. I've removed this modification, which re-enabled shell integration, but this didn't fix the issue of the slow activation, if anything it's made it slower.

I've now set python-envs.terminal.autoActivationType to shellStartup and this works much better.

[karthiknadig]

You need both Shell Integration and Shell Startup for the ideal experience. I am glad it worked for you.

[Simon-Stone]

I've now set python-envs.terminal.autoActivationType to shellStartup and this works much better.

Found this issue after going nuts over it. This fixed it for me. Thanks!!