Reduce Firefox Memory Usage when Minimize

Everybody knows that Firefox has problem with the memory usage.
Sometimes it can reach to hundreds of megabytes. But here is a tricks on how
to reduce the memory usage when you minimize your Firefox.

1. Type about:config in Firefox address bar and press Enter.
2. Right click in the page and select New > Boolean.
3. Type config.trim_on_minimize in the box that pops up. Press Enter.
4. Select True and then press Enter.
5. Restart Firefox.

What it will do is, when each time you minimize your Firefox, the memory
usage will dramatically drop down to 10Mb (this is what happen on my PC) but
then it will slowly increase up to 50Mb. When you maximize it back, it will stay
on 50Mb or maybe 70Mb.