How much memory is Firefox using right now?

1. Press CTRL+SHIFT+ESC to load the Task Manager window
2. Click the Processes tab at the top. (Click once near the top of the window if you don't see tab
3. Find firefox.exe, and see how many kilobytes of memory it's using.

Showing around 80MB when Firefox first starts is normal. Right now, I have 75 tabs open and it's using 500MB - this varies a lot depending on what you have in the tabs.

Other than high memory usage, what other problems are you experiencing? (Examples include slowness, high CPU usage, and failure to load certain sites)

Many of these issues, including high memory usage, can be caused by misbehaving add-ons. To see if this is the case, try the steps at Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems. Outdated plugins are another cause of this issue - you can check for this at http://www.mozilla.com/plugincheck

when I open firefox spends about "35MB Mem usage", and "40MB VM size". (On task manager) after I used it long enough memory that continues to grow without being able in the cut. There had even too low virtual memory warnings.

this is not like when I use chrome, chrome always freeing memory that is not in use any longer by the tabs that have closed. thus can be more efficient in memory usage.

Can you explain this problem?

if I open firefox why not open directly? others as if I opened IE8 or Chrome. it only takes 2-3 seconds. whereas firefox up to 15 seconds even if the CPU usage of more than 50%.

There's one more thing I want to ask. whether each tab that has been in close does not release the memory that has been in use?