Mozilla Firefox memory leak problem is a headache for most of its users. Here is a tip to reduce Mozilla Firefox usage when it is minimized.
Type about:config in Firefox address bar and press Enter.
Right click in the page and select New > Boolean.
Type config.trim_on_minimize in the box that pops up. Press Enter.
Select True and then press Enter.
By doing this, the memory usage will drop to around 10MB every time you minimize it and increase slowly up to around 50MB. When it is maximized, the memory usage will be around 50MB – 70MB. Although this is not the best solution for reducing the Firefox memory leak, it may solve high usage of memory of this browser.