Newcomer to Rustlang - VScode slows down my Mac?


I’ve decided to delve into Rustlang. I’m using VSCode as my editor of choice so I downloaded and installed the Rust (rls) extension, and it had a disasterous effect on my machine’s performance.

I have an Apple Mac Pro with 32GB of RAM and running macOS Mojave bete 11, but after loading the extension I was getting agonising pauses and spinning beach balls left right and centre, and this was not just in VSCode but right across the system!

Somebody on Twitter suggested adding "": 1 to my config but this didn’t make any difference.

I’ve just been though my VSCode extensions and deleted a whole bunch of them and am going to try the Rust (rls) extension again…

Okay, I’ve tried it again, and while performance is not as bad as before, I’m still getting random pauses and spinning beach balls, which is so annoying. Surely someone out there has figured out how to avoid this!

Any ideas, anyone?


I’ve uninstalled the Rust (rls) extension and have installed Alexey Kalita’s Rust extension. That also seems to have RLS integration and critically it doesn’t seem to screw up my machine!

It only has 114,000 downloads as opposed to Rust (rls)'s 312,000 downloads, but I like to think that I’ve never been one to follow the crowd (or at least not the larger crowd)!

So, we’ll see how things go. You may hear from me again, with more embarassing newbie questions!


I’ve been using VSCode for debugging Rust for a long time on a MacBook Pro with 16 GM RAM running High Sierra (10.13.6) and have encountered no such problems.

Which extension are you using? And do you have to install a separate package to get the debugging?

Now you’re asking hard questions about things I haven’t looked at in months. I don’t recall having to install a separate package for debugging.


CodeLLDB 0.8.9
Emacs Keymap 0.1.1 (Yeah, I’m one of those annoying emacs guys.)
Rust 0.4.2
Rust (rls) 0.4.10
Rusty Code 0.19.1

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CodeLLDB looks suspiciously debugger-like. I’ll check it out in a few minutes. I’m busy scaling the intellectual heights of Hello World and Guessing Game in the RustLang eBook, which I have to say seems very well written!
Thanks for the heads-up!

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As I thought, CodeLLDB is the debugger. Is there any chance that you could let me know what one of your launch.json files looks like?

    "version": "0.2.0",
    "configurations": [
            "type": "lldb",
            "request": "launch",
            "name": "Debug",
            "program": "/Users/alan/Documents/Eclipse/multicell/target/debug/multicell",
            "args": [],
            "cwd": "/Users/alan/Documents/Eclipse/multicell",
            //"preLaunchTask": "/Users/alan/.cargo/bin/cargo",
            "sourceLanguages": ["rust"],    

As you can see, I used to use Eclipse.

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Cool, thanks Alan! I’ll take a look at it in the morning. It’s getting a bit late here in London, England!

Welcome to Rust! You have a wonderful journey ahead of you, and I am certain you’ll learn a LOT about programming, computers, and software engineering in general!

I don’t know much about Macs, nor about VScode, but I took the liberty of updating your topic title, in the hopes of attracting people who can help you better.

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Hi @alanhkarp, you might be interested in this post Setting up a generic launch.json for Rust in VSCode [SOLVED] in which I have sussed out how to have a single generic launch.json for a number of Rust projects.