felosi,
The behavior that you are asking about is completely normal. Here is a look at my /proc/meminfo file on my Internet browsing workstation.
$ cat /proc/meminfo
MemTotal: 1035776 kB
MemFree: 111596 kB
Buffers: 118448 kB
Cached: 516620 kB
SwapCached: 0 kB
Active: 361316 kB
Inactive: 372740 kB
HighTotal: 131008 kB
HighFree: 252 kB
LowTotal: 904768 kB
LowFree: 111344 kB
SwapTotal: 2093032 kB
SwapFree: 2093032 kB
Dirty: 4 kB
Writeback: 0 kB
Mapped: 136260 kB
Slab: 181236 kB
Committed_AS: 167136 kB
PageTables: 1388 kB
VmallocTotal: 114680 kB
VmallocUsed: 4460 kB
VmallocChunk: 110128 kB
HugePages_Total: 0
HugePages_Free: 0
Hugepagesize: 4096 kB
You can see that I have 1 GB of RAM and about 89% of it is allocated. I have about 11% free.
MemTotal: 1035776 kB
MemFree: 111596 kB
You can probably get rid of some of those processes but you have to learn what each one does before you know if and how to turn it off.
$ ps -e | wc -l
77
$ ps -U turtle | wc -l
32
Here you can see that I have a total of 77 processes running. Of those 32 are being run by the turtle user account, my normal user Internet access user account. That leaves 77 - 32 = 45 system processes. Of the 45 system processes about a half dozen are things that I don't really need such as the S.M.A.R.T. disk drive monitor daemon. So I could probably get the computer down to about 40 system processes, but that wouldn't free up any memory. That's because the operating system will find something else to do with the RAM such as increasing the size of the disk cache or of the soft fault cache. I forget the real name of the soft fault cache at the moment.
