Mac too slow with many browser tabs — what to do

You have 80 tabs open across two windows. The Mac is dragging, the fan is on, the battery is draining faster than usual. Closing all the tabs feels like losing context, but something has to give. Here’s how to find the worst offenders without blowing up your session.

Why tabs hurt

In Chrome, Edge, Brave, and Arc (Chromium browsers), each tab is a separate process. Memory and CPU scale roughly linearly with tab count. Safari is smarter — it consolidates tabs into fewer processes and aggressively suspends background ones — but a Safari tab playing video or running heavy JavaScript still costs the same as anywhere else.

Tabs hurt in three ways: RAM (each tab holds its DOM, JavaScript heap, and decoded images), CPU (background scripts, animations, autoplay video), and disk (cache writes, IndexedDB, service workers).

Find the offenders

1. In Chrome/Edge/Brave, press shift+escape (or Window menu - Task Manager). This shows per-tab CPU and memory. Sort by either.
2. In Safari, open Activity Monitor and filter for "Safari" — each "Web Content" process is a tab or group of tabs.
3. Look for the worst offenders. A tab using 500MB+ of RAM, or sustained 10%+ CPU in the background, is unusual and worth closing.
4. Close tabs with autoplay video. Even muted, video tabs burn CPU decoding frames you're not watching.
5. Watch for service workers. Some sites run code even after the tab is "closed." Restart the browser fully to clear them.

Make 80 tabs livable

You don’t have to close them. A few habits make the cost manageable:

• Use a tab-grouping or session manager (built-in on most browsers now). Move inactive tabs into a group you collapse.
• Suspend tabs you’re not using. Chrome’s “Memory Saver” mode does this automatically; extensions like OneTab or The Great Suspender work too.
• Quit and relaunch the browser once a day. This drops accumulated leaks and flushes service workers.
• Pin the tabs you actually use to the left; let the rest stay collapsed.

Watching the cost

Per-tab task manager numbers tell you which tab. They don’t tell you the system-wide cost — total CPU, memory pressure, swap usage — which is what actually makes the Mac feel slow. For that you want a menubar view that shows the aggregate.

Beacon shows CPU, memory pressure, and swap in the menubar so you can see when “I have a lot of tabs open” tips into “the Mac is now slow.” $14.99 lifetime. Download Beacon if you want to see the cost in real time.

When the answer really is close tabs

If memory pressure is consistently red with your normal tab load, no amount of suspension will fix it — you need fewer active tabs or more RAM. A 16GB Mac can usually handle 30-50 tabs comfortably; 200 tabs is going to hurt on any consumer Mac no matter how new.