Slack is, essentially, a browser
The root cause of Slack's high memory usage is a framework called Electron. Electron takes the Chromium browser engine — the same core that powers Google Chrome — and packages it directly inside the application. So when you open Slack, you are not launching a lightweight chat client. You are launching a full web browser that has 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 memory footprint is already substantial before you have opened a single conversation. This is the primary reason why Slack uses so much RAM even at idle.
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 are 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 carries its own memory overhead. Slack's RAM usage compounds quickly once you factor in two, three, or more active workspaces — which is a common reason people notice Slack high RAM usage on multi-team accounts in particular.
The invisible background work
Even when you are not reading or sending anything, Slack keeps several processes running continuously:
- Real-time message sync: polling servers across every channel in every workspace you have 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 background activity is why Slack's memory usage creeps upward throughout the day. A fresh startup that sits at 400 MB can quietly become 1.5 GB by late afternoon — even if you have not done anything unusual. If you are wondering why Slack uses so much memory after a long session, this sustained background work is the answer.
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, that is a genuine operational advantage.
Rewriting the app natively would take years of engineering effort and would not add a single visible feature for users. Slack's high memory usage is structural, not accidental — the underlying architecture is not 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 is not 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: a fraction of what the official app consumes.