you can verify it if you want..
first,down run the firefox ultimate optimizer yet and do this:
1. click "ctrl + alt + del" or access your task manager
2. click the "view" tab and select "select columns"
3. within "select columns",check "virtual memory size"
4. without the firefox ultimate optimizer on,the "memory usage" and "vm size" should basically be just the same
now run this so called firefox ultimate optimizer and observe the "memory usage" column and "vm size" column..