Why does the GMail web page use so much RAM?

Question

When I log into my GMail account (using Firefox 31.0 via Ubuntu 14.04 64bit), if I save that web page to my desktop, the file size is 1.3 MB.

However, if I look at Firefox's RAM consumption before logging into GMail, and then after. GMail increases RAM consumption by well over 200MB!

Even when I run Firefox in safe mode (which disables plug-ins/extensions), I see this huge increase in RAM consumption upon logging into GMail.

Surely, behind the scenes, the GMail web application hasn't just downloaded and cached 200+ MB of data so instantly.

I thought maybe it might be buffering some local cache that it might have been using in an earlier session, but I used another web browser (that I had never logged into GMail with before), and it too used a lot more RAM after logging into GMail.

How is a 1.3MB web page taking up over 200 MB of RAM each time you log into it?

What inefficiency or caching-strategy can account for this website consuming 200 times (in RAM) the amount of data that it actually displays?

Answer 1

Gmail's web page is running MANY scripts in the background on timers, etc. These take up memory as they work. Your "Saved" copy won't have these scripts (at least not in a working/running manner), and their associated objects in memory.

If you use a memory profiler (built into most modern browsers' development tools) you can see what's actually using memory.

When I take a snapshot of my "idle" gmail page, there's 136,441 objects loaded in memory.

Those objects range from using 32 bytes of memory, to a few kilobytes, up to over 4 megabytes, depending on the object.

And that doesn't include the memory used by the browser to actually render the page to you.

• Perhaps try the "Basic HTML" version, as it should use much less memory. It's available at https://mail.google.com/mail/?ui=html.