VS Code Code Runner takes several seconds to run simple C programs on Windows

Hello Pranay,

Your 0.21 s measurement covers only compilation. “Run Code” does more than that: Code Runner compiles the file, then starts the generated .exe, either in the Output panel or in the integrated terminal. The best approach is to time each of these stages separately.

Step 1: Time the executable by itself

In PowerShell, in the folder with your program, compile once and then run the .exe several times:

powershell

gcc hello.c -o hello.exe
Measure-Command { .\hello.exe } | Select-Object TotalMilliseconds   # 1st run right after compiling
Measure-Command { .\hello.exe } | Select-Object TotalMilliseconds   # 2nd run
Measure-Command { .\hello.exe } | Select-Object TotalMilliseconds   # 3rd run

• Only the first run after compiling is slow: the delay is probably antivirus scanning of the freshly created .exe (Microsoft Defender real-time protection checks new executables before they run). See Step 4.
• All runs are fast: the program and GCC are fine. The delay comes from Code Runner or the terminal, so go to Step 2.
• All runs are slow: something in the system is affecting every process start. Test a plain cmd /c exit the same way for comparison.

Step 2: Compare Code Runner’s two run modes

Code Runner has a setting called code-runner.runInTerminal. Try both values in settings.json:

json

"code-runner.runInTerminal": false,
"code-runner.showExecutionMessage": true

• false (Output panel): no terminal is involved. With showExecutionMessage on, the Output panel shows [Running] and [Done] messages with the elapsed time.
• true (integrated terminal): if this mode is noticeably slower, especially on the first run, the cost is the terminal and shell starting up, not your program.

Step 3: If the terminal is the bottleneck, check your shell startup

In a regular PowerShell window, compare startup with and without your profile:

powershell

Measure-Command { powershell -Command exit }            | Select-Object TotalMilliseconds
Measure-Command { powershell -NoProfile -Command exit } | Select-Object TotalMilliseconds

A large difference means a slow PowerShell profile, such as modules or prompt themes loading at startup. You can fix the profile, or set the VS Code default terminal profile to Command Prompt and compare again.

Step 4: If antivirus scanning is the cause

Don’t turn Microsoft Defender off. Windows 11 supports a Dev Drive: if you keep your projects there, Defender scans them in performance mode, which is asynchronous. Microsoft documents this as a safer alternative to folder exclusions.

• Set up a Dev Drive on Windows 11
• Protect Dev Drive using performance mode

If the cause is still unclear, please reply with:

1. How long the delay is, in seconds.
2. Your code-runner.runInTerminal value.
3. The three timings from Step 1.

With those numbers, the cause can be pinned down exactly.

Hope this helps. If it does, please consider accepting the answer.

Fontes:

• Code Runner – repositório oficial (configurações)
• Set up a Dev Drive on Windows 11 – Microsoft Learn
• Protect Dev Drive using performance mode – Microsoft LearnHello Pranay, Your 0.21 s measurement covers only compilation. “Run Code” does more than that: Code Runner compiles the file, then starts the generated .exe, either in the Output panel or in the integrated terminal. The best approach is to time each of these stages separately. Step 1: Time the executable by itself In PowerShell, in the folder with your program, compile once and then run the .exe several times: powershell

    gcc hello.c -o 
  

  • Only the first run after compiling is slow: the delay is probably antivirus scanning of the freshly created .exe (Microsoft Defender real-time protection checks new executables before they run). See Step 4.
  • All runs are fast: the program and GCC are fine. The delay comes from Code Runner or the terminal, so go to Step 2.
  • All runs are slow: something in the system is affecting every process start. Test a plain cmd /c exit the same way for comparison.
  Step 2: Compare Code Runner’s two run modes Code Runner has a setting called code-runner.runInTerminal. Try both values in settings.json: json

    "code-runner.runInTerminal"
  

  • false (Output panel): no terminal is involved. With showExecutionMessage on, the Output panel shows [Running] and [Done] messages with the elapsed time.
  • true (integrated terminal): if this mode is noticeably slower, especially on the first run, the cost is the terminal and shell starting up, not your program.
  Step 3: If the terminal is the bottleneck, check your shell startup In a regular PowerShell window, compare startup with and without your profile: powershell

    Measure-Command
  

  A large difference means a slow PowerShell profile, such as modules or prompt themes loading at startup. You can fix the profile, or set the VS Code default terminal profile to Command Prompt and compare again. Step 4: If antivirus scanning is the cause Don’t turn Microsoft Defender off. Windows 11 supports a Dev Drive: if you keep your projects there, Defender scans them in performance mode, which is asynchronous. Microsoft documents this as a safer alternative to folder exclusions.
  • Set up a Dev Drive on Windows 11
  • Protect Dev Drive using performance mode
  If the cause is still unclear, please reply with:
  1. How long the delay is, in seconds.
  2. Your code-runner.runInTerminal value.
  3. The three timings from Step 1.
  With those numbers, the cause can be pinned down exactly. Hope this helps. If it does, please consider accepting the answer. Fontes:
  • Code Runner – repositório oficial (configurações)
  • Set up a Dev Drive on Windows 11 – Microsoft Learn
  • Protect Dev Drive using performance mode – Microsoft Learn