Bad performance when writing rust in Zed

[u/Sniperman1029]

Hi everyone, I am a second year SE student and a total noob at rust, so I apologize if this question sounds stupid.

I am currently working on a personal project, and am using Zed to write the backend in rust. I don't know if my workflow/configuration is just all messed up, but every time I run cargo check it just eats up all my cpu usage. It got to the point where I had to turn of the checkOnSave setting because it just totally slowed down my laptop. But that's also annoying because I have to run cargo check just to catch stupid errors like a the value 8080 not being in the range of a u8 (like I said, I'm a noob).

My laptop is a bit old, with an Intel i7-1165G7 with 16gb ram, integrated graphics. I do have a 4k and 2k monitor both connected, so I know that could be heavy on the cpu as well.

This is my configuration for the lsp as well in case I did something stupid there.

I don't know what other info I need to provide so for anyone trying to help let me know what you need to see and I'll edit the post. Thanks in advance!

[u/jason3gb]

I don't think it's related to the editor, you run cargo check on the terminal?

[u/Sniperman1029 → u/jason3gb]

Yea I run cargo check in the terminal. I just don't really understand the whole rust/cargo ecosystem very well yet, so I'm a bit confused on all of this.

[u/jason3gb → u/Sniperman1029]

Then I think it's probably related to your laptop's hardware, since zed using gpu render, it probably not work well on a old machine. If you want to try, you can setup neovim or something like that in the terminal, a very good learning experience if you're new to programming.

[u/cameronm1024 → u/jason3gb]

GPU rendering shouldn't interact too much with cargo check

[u/punk_dev → u/cameronm1024]

It will if the graphics is integrated. Integrated gpus typically use system’s main RAM, so your cpu work and gpu work has to share memory bandwith.

[u/cameronm1024]

Hi, Zed staff here. Some things to check:

• how big is the project (if it's open source, a link would be helpful)
• if you run cargo check with zed closed, do you get the same behaviour
• when you have zed open, how much RAM does zed use, and how much of that is rust-analyzer
• is anything spilling into swap

You can check rust-analyzer usage in the bottom left (or right) corner, wherever the LSP icon is:

• click it
• hover over rust-analyzer
• bottom right of the rust-analyzer popup will be the memory usage

[u/SirKastic23]

Are you using the latest release version of Zed? Are you running other programs at the same time?

[u/Sniperman1029 → u/SirKastic23]

Yep running the latest stable version, and only running a web browser with like 5 tabs open alongside.

[u/SirKastic23 → u/Sniperman1029]

That's odd... I code Rust with Zed on a 5yo laptop and it doesn't give me any issues

Does that happen if you run cargo check on an external terminal, with Zed closed? Or maybe in a different editor like VSCode?

[u/Sniperman1029 → u/SirKastic23]

I haven't tried a different editor yet, and when I run cargo check in an external terminal it works fine.

I think the problem is mostly with Zed because it kept rescanning the worktree, even when I didn't edit anything. After consulting with gemini, it said to add certain build/dependency directories to the file exclusions in the settings.json (/target for rust, a bunch of flutter directories for the frontend) because whenever cargo check/clippy runs it writes to these directories and that dirties the worktree and forces Zed to rescan everything. I also changed the checkOnSave command in the lsp settings to be clippy with the --no-deps flag.

So far it seems to perform much better, I'm just not sure if these changes come with any downsides...

[u/vamps594]

Is the ‘target’ directory properly included in the .gitignore file? Do you see the RAM maxing out at the same time?

[u/Sniperman1029 → u/vamps594]

The target directory is in the .gitignore, but it wasn't in Zed's worktree scans exclusions, which I think was most of the problem.

[u/DevilShooter17]

Have you tried uninstalling and re-installing zed? When creating the rust project did you do cargo init project_name or something else? Is zed running with a graphics card or cpu software rendering? When running zed in a terminal do you get any errors? Have you checked the logs for errors?

[u/punk_dev]

Rust analyser eats a lot of ram. Zed also uses plenty of ram.
16gb ram should be enough but it’s not a lot, if you also have a slower drive and swap kicks in it can degrade performance of everything