High CPU usage and poor performance using the integrated terminal on Windows

[seraku24]

• VSCode Version: 1.4.0
• OS Version: Windows 10 - Version 1511 (OS Build 10586.494)
• Installed Extensions: csharp (1.3.0)

Steps to Reproduce:

1. Launch VS Code.
2. Open the integrated terminal (CTRL+~).
3. Type some text into the terminal.

Expected:

The text appears promptly upon entering, and CPU usage shows no spikes.

Actual:

The text does not appear immediately. Task Manager shows one of the VSCode processes is using nearly 100% of a CPU core for around 1-2 seconds. Afterwards, the input text appears in the terminal, and CPU usage drops to minimal values.

Notes:

After rebooting my machine, VSCode initially performs as expected. However, performance will eventually drop considerably and stay consistently poor even after relaunching VSCode. Only a full reboot seems to temporarily address the issue.

While I do not have full Visual Studio or the performance toolkit on this machine to be able to capture more detailed profiling data, I was able to use Task Manager to capture a minidump of the process during the high CPU usage. As the resulting file is about 350MB, I will defer uploading until someone requests it.

DxDiag.txt

[Tyriar]

I haven't experiences any performance issues in particular recently, I spend most of my time on Linux though. I have a few follow up questions:

• Are you using cmd.exe? Does this spike occur in the regular cmd.exe if so?
• What does your setting.json file look like? What is your `%COMSPEC% environment variable set as?
• Which process is 100%? The arguments on the process tell which one it is (eg. --type=renderer, ./terminalProcess, etc.)
• Do you think the overall slow down could be not to do with the terminal?

[jasonboninger]

Hi, I am experiencing very similar symptoms. Running on Windows 7, and to answer your questions:

• Yes, I am using cmd.exe because that is what it defaults to.
• I have not customized any of the terminal settings in settings.json except for the line height and cursor blink.
• I am not quite sure how to answer which process is spiking. Not familiar enough with processes, just can see my CPU usage spike.
• The terminal outside of VSC runs exactly as expected. Instant typing and no performance spike.

Hopefully that helps. I love the integrated terminal, but it so dang slow right now it's nearly unusable!

Thanks for making a great application.

[Tyriar]

Is it possible to right click or double click the process in the task manager to see more detail on it?

[jasonboninger]

I'm sorry, don't know how to do what you are asking in the task manager without much more detailed instructions. I did notice that running VSC all by itself (closing Chrome which where I test my applications) reduces the lag by a lot.

[seraku24]

Hi, @Tyriar. Here are my responses to your questions:

• Yes, I am also using cmd.exe. And, no, I have not experienced poor performance with the CLI itself.
• Here are the only two customized settings in my settings.json:

"editor.snippetSuggestions": "none",
"editor.tabCompletion": true

• Task Manager does not show the command-line arguments, but SysInternals' Process Explorer does. Here is the full command for the process in question:

"C:\Program Files (x86)\Microsoft VS Code\Code.exe" --type=renderer --no-sandbox
 --lang=en-US --app-user-model-id=Microsoft.VisualStudioCode --node-integration=true
 --background-color=#1E1E1E --enable-pinch --device-scale-factor=1 --num-raster-threads=1
 --content-image-texture-target=3553,3553,3553,3553,3553,3553,3553,3553,3553,3553,3553,3553,3553,3553
 --video-image-texture-target=3553 --channel="7024.1.1354609598\1806532456" /prefetch:1

Finally, here is some new information regarding my repro scenario:

After waking my machine from a suspended state (so not a reboot), I found VSCode initially was performing well. I should note the process above does consume around 50% of a core while typing occurs in the terminal, dropping to idle about 1-2 seconds after typing stops.

Unfortunately, it was not too long before the terminal, again, became periodically unresponsive. At this point, I could confirm that the process above is the one spiking. Seeing as the process appears to be related to rendering, it would certainly explain why the visuals are lagging behind the typing.

Since I forgot to include it before, here is a capture of all of the running processes:
Processes.tabulated.txt

[Tyriar]

Thanks @seraku24, so this only occurs when typing? The renderer process is where all the key presses are handled initially before being passed over to xterm.js (Code.exe ./terminalProcess) for processing.

[Tyriar]

This may be related to #9244

[seraku24]

Correct, all of the VSCode processes run at minimal CPU usage normally. Just typing one letter will result in the renderer process taking a lot of CPU.

But what I have found is that you do have to actually type something that changes the console screen buffer. It is not simply the key presses themselves. For instance, pressing backspace at an empty prompt produces no change from minimal CPU usage. As such, it would seem the performance is not really tied to the input itself but whenever the console screen buffer is altered. This appears to match the behavior described in the issue you mentioned.

[carlin-q-scott]

I tried using the integrated terminal for a node.js project in Windows but it greatly reduces performance of all the npm commands, especially "npm install". npm does a fair amount of fancy stuff with the terminal so I'm guessing it's not helping the performance but the difference between "Integrated Terminal" and a normal command prompt is stark.