Taking a look from your screencaps -- I wonder, do you have Defender installed? I never seen msmpeng.exe appear on my system before, despite it is a Windows Defender --
Process source reference --
msmpeng.exe - What is msmpeng.exe?
I'm tempted to wonder why your Firefox is eating almost 3Gb+, and as much know what are your other 80+ running processes eating that much off your base memory -- but my guess is this, I figure you have several programs running simultaneously, all wanting a piece of your base memory, and to some extent that some are set on auto-update (
which on some programs tend to cling on the process quite hard, thus adding a toll to the memory )
Even if your screencap reads 30-40% usage on memory, it's the number of processes that are taking your gear a beating -- try to find out what are these processes; some may be needed, some are just add-on programs from manufacturers that are best set into manual updating mode, or disabled altogether.
A quick check over the Web should help you determine the use of these processes -- on the search bar, type the keyword process ( ex:
MsMpEng.exe ) plus the keywords "
what is this process" -- there's a good number of sites that'll will help you inform you; some of these sites will also give you an idea to either retain / disable the process
But
note -- make sure you know before you do any chances to your system that you prepare it for the worse, so a system restore is in order before you try to disable one-by-one a certain process
It's a slow and tedious thing, but I'm sure you'll be able to find the programs that are putting a load on your system