Slack is, essentially, a browser
Slack is built with a framework called Electron. Electron takes the Chromium browser engine — the same core that powers Google Chrome — and packages it together with the application. So when you open Slack, you're not just running a chat app. You're running a full web browser that's been configured to display one website.
Chromium alone requires 100–200 MB of RAM before any application logic runs on top of it. Add Slack's own code, and the baseline is already substantial before you've opened a single conversation.
Each workspace multiplies the load
Like Chrome handles multiple tabs with separate processes, Slack handles multiple workspaces — and it does so with distinct processes for each. If you're connected to three workspaces, you may have eight or more processes running simultaneously. You can verify this yourself:
- Windows: Open Task Manager, find Slack, and expand the entry
- macOS: Open Activity Monitor and search for "Slack"
- Linux: Run
ps aux | grep -i slackin a terminal
Each of those processes has its own memory footprint. They add up fast.
The invisible background work
Even when you're not reading or sending anything, Slack keeps several processes running continuously:
- Real-time message sync: polling servers across every channel in every workspace you've joined
- Spell-checker: running a full spell-check engine passively in the background
- Auto-updater: silently checking for and staging new versions
- Crash reporter: collecting diagnostic data and preparing reports
This is why Slack's memory usage creeps upward throughout the day. A fresh startup at 400 MB can quietly become 1.5 GB by late afternoon — even if you haven't done anything unusual.
Why Slack built it this way — and why they won't change it
Electron is a practical engineering choice. One codebase, one team, three operating systems. Features ship simultaneously to Windows, macOS, and Linux. For a company at Slack's scale, this is a real operational advantage.
Rewriting the app natively would take years of engineering effort and wouldn't add a single visible feature for users. The memory cost is a deliberate tradeoff, and the architecture isn't going to change.
What you can actually do about it
There are workarounds — quitting unused workspaces, disabling hardware acceleration, closing Slack entirely when you step away. We cover these in detail in our guide to reducing Slack's memory usage.
The more permanent fix is a client that isn't built on Electron. msga is a native Slack client — it connects to the same Slack servers you already use, but runs without a bundled browser engine. At idle, it uses around 60 MB of RAM.